Count number of distinct pairs whose sum exists in the given array. Mar 28, 2023 · Given an array arr [] of size N.


Count number of distinct pairs whose sum exists in the given array. For each number, change each digit to one of the other 9 digits and check if it is in the hashset. Finally, return the number of pairs. Given two unsorted arrays, find all pairs whose sum is x | GeeksforGeeks GeeksforGeeks 951K subscribers Subscribed Can you solve this real interview question? Count Number of Pairs With Absolute Difference K - Given an integer array nums and an integer k, return the number of pairs (i, j) where i < j such that |nums [i] - nums [j]| == k. Jul 26, 2025 · To check if a pair with a given sum exists in the array, we first sort the array. Jul 23, 2025 · The 2-Sum problem is a popular algorithmic challenge where the goal is to identify two distinct elements in an array whose sum equals a specific target. . In this problem, We have to print the triplet and also return true, if such a triplet is present in the array. Sep 1, 2025 · Now, compare the sum of elements at these pointers: If sum = target, store the pair and skip duplicates to ensure they are distinct. If you are interested in related problems (with sum of more than 2 numbers), see "Sum-subset with a fixed subset size" and "Finding three elements in an array whose sum is closest to an given number". My current solution takes O(n*log(n)) time (code snippet below). I was able to solve problem in O (n2). Pair (x,y) and Pair(y,x) are considered as the same pair. Your task is to count all the distinct pairs in ‘ARR’ such that their sum is equal to ‘TARGET’. We know, if a and b are elements of array A where a <= b and they make a pair then, Jan 8, 2025 · Given an array arr [], and an integer target, find all possible unique triplets in the array whose sum is equal to the given target value. You may return the combinations in any order. So add that count to answer. We are given an array of, let's say, arr [] of integer values of any respective size and the task is to calculate the count of the number of distinct pairs available in a given array whose sum also exists in the same array. For example, 2373 is made up of three distinct digits: 2, 3, and 7, where 7 is the largest among them. In case the value of x is zero, then it can be paired only with elements having 0 mod value. Store all the possible sums into an unordered_set. Below is the Algorithm - Create a map to store frequency of each number in the array. Jul 12, 2025 · The idea for this naive approach is to use nested loops to check all possible pairs to find the unique pairs of elements in the array with the sum greater than 0. Increment the counter accordingly. Examples: Input: arr [] = {1, 1, 2} Output: 4 (1, 1), (1, 2), (2, 1), (2, 2) are the only possible pairs. This frequency count of array elements is stored in hash. Also calculate mobius of each d present in this array. Write a Java Program to find pairs with given sum in a sorted array. Finding Pairs With a Certain Sum in Python, Java, C++ and more. Aug 16, 2024 · Conclusion Finding whether a pair with a given sum exists in an array is a common problem that can be efficiently solved using hashing. So far I am only capable find which pairs whose result already exists. Can anybody help me in finding a better solution, O(n) or O(lgn) may b Dec 31, 2017 · Given an array, I would like to display the count of distinct pairs of elements whose sum is equal to K - I've written code as below, but I am unable to put array_diff to good use :\\ &lt;?PHP func Python – Find All Pairs in an Array Whose Sum Equals a Given Number This tutorial explains how to find all pairs in an array that add up to a given target sum. (5, 2): Sum = 5 + 2 = 7, which lies in the range [4, 7 In-depth solution and explanation for LeetCode 1865. Write a program that, Given an array of n integers and given a number K, determines whether or not there exist two elements whose sum is exactly K. Jul 11, 2025 · Naive Approach: The simplest approach is to iterate through every pair of the array but using two nested for loops and count those pairs whose sum is divisible by 'K'. Aug 28, 2024 · Given an array arr [] of n distinct integers and a target value, the task is to check whether there is a pair of elements in the array whose product is equal to target. If the sum of the elements at these pointers equals target, we update the pair counter and skip duplicates to ensure they are distinct. Examples: Nov 5, 2022 · You don't need to count pairs if the result already exists, so you don't need to count 2+2=4 because 4 already exists from 1+3=4. Add a positive integer to an element of a given index in the array nums2. 6K subscribers 395 Jan 18, 2023 · The problem statemnt is :- find total number of triplet in an array such that sum of a [i],a [j],a [k] is divisible by a given number d and i<j<k. Data Structures: A sorted list (nums. Your task is to calculate the number of ways to pick two different indices i < j, such that a [i] + a [j] is divisible by k. count] { if x + y == target { Oct 11, 2024 · Given an array arr [] and a target value, the task is to find all possible indices (i, j) of pairs (arr [i], arr [j]) whose sum is equal to target and i != j. Given an array of n integers and a target number, write a program to find whether a pair sum exists in the array or not. I have tried this problem using a hash table to store entries for the sum of array elements, but it is not an efficient solution. Array - 16: Check if there exists a pair which matches given Sum Coding Simplified 43. May 10, 2023 · Then, we use set and array slicing to efficiently find all distinct pairs whose difference is equal to k. If it contains the number it means that we iterated over its complementary before, so we can just add one pair and remove the number from the list of complementaries. Aug 13, 2025 · [Naive Approach] Generating All Triplets - O (n^3) Time and O (1) Space A simple method is to generate all possible triplets and compare the sum of every triplet with the given target. com/channel/UCs6sf4iRhhE875T1QjG3wPQ/joinPatreon 🚀 https://www. I have tried a multiple solutions but the solutions all reached o (n 3). A subarray is a contiguous part of an array. If there exists no such pair with sum equals to 'TARGET', then return Can you solve this real interview question? K-diff Pairs in an Array - Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array. We will look into problem statement, sample data, and Python Program. Input: Input consists of 3 lines. This array element can be paired with array elements having mod value k-x. Input: arr [] = {1, 2, 3} Output: 9 Naive approach: The simple solution is to iterate through every possible pair and add them to a set and then find out the size Question: Given an unsorted array of positive integers, is it possible to find a pair of integers from that array that sum up to a given sum? Constraints: This should be done in O (n) and in-place (without any external storage like arrays, hash-maps) (you can use extra variables/pointers) And to get 2nd part of S where d in (1e7, 1e9]: we create an array which contains all factors in (1e7, 1e9] of each element (these are ai / (10 smallest factors of ai)), then we can loop through the multiples of each element of this array and count how many of them are present. For example, given the array {1, 7, 5, 9, 2, 12, 3} and the difference k = 2. At each step, there are two choices: either add the current element to the running total or subtract it. enumerated() { for y in numbers[i+1 . Otherwise, we return empty array. Jul 23, 2025 · Given an array arr [] consisting of N integers, the task is to count the number of distinct pairs (arr [i], arr [j]) in the array such that the average of pairs is also present in the array. We iterate over the sorted array and check if the element arr [i]+k exists in the subarray arr [i+1:]. After completion of second traversal, we Jul 23, 2025 · Target Sum using Recursion: The problem can be solved by recursively exploring all possible ways to combine the integers in the array while adding or subtracting them to reach the target sum. Example 1:Input:N = 4, K = 6arr [] = Jun 15, 2013 · We are given an array A and an integer Sum, we need to find all distinct sub sequences of A whose sum equals Sum. Jul 12, 2025 · In order to find all the possible pairs from the array, we need to traverse the array and select the first element of the pair. Each pair should be reported only Question: Problem Statement Given an array of 'n' distinct integers, write a program to find if there exists any pair of integers whose sum is 'X', with linear time complexity. Jul 11, 2025 · Given an array of N elements, the task is to find all the unique pairs that can be formed using the elements of a given array. patreon. Mar 7, 2025 · Finding pairs in an array that sum up to a target is a common problem with different trade-offs. Nov 7, 2018 · 3 I want to find all the unique pairs whose sum will be equal to a given sum. This article provides detailed examples and explanations. If a valid pair is found, we return it. You have to find the maximum sum of a pair of numbers from nums such that the largest digit in both numbers is equal. Sep 23, 2021 · Problem Statement:- Given an array of N integers, and an integer K, find the number of pairs of elements in the array whose sum is equal to K. Programming competitions and contests, programming communityCount number of distinct pairs whose sum exists in the given array ("In less then n2") Oct 2, 2022 · Count number of distinct pairs in the array whose sum exists in the given array ||codezinger | Programming Geek 827 subscribers Subscribed Jul 23, 2025 · Given an array arr [] and a positive integer k, the task is to count all pairs (i, j) such that i < j and absolute value of (arr [i] - arr [j]) is equal to k. Increment count for x in hash. This article provides a clear explanation and code examples. Given an array, task is to find pairs in array whose sums already exist in array in C++. Jul 23, 2025 · Algorithm: Use nested loops to get all possible sums of elements of the array. Examples: Input : arr[] = {5, 4, 10, 15, 7, 6}, x = 5 Output : 1 Explanation : (10 ^ 15) = 5 Input : arr[] = {3, 6, 8, 10, 15, 50}, x = 5 Output : 2 Explanation : (3 ^ 6) = 5 and (10 ^ 15) = 5 A Simple solution is to traverse each element and check if there Jul 17, 2021 · For count, loop over map1, and for each entry, calculate the count from map2 that has sum equal to tot, and calculate the number of pairs. Problem Statement Given an array arr and a target sum target, find all unique pairs (a, b) in the array such that a + b = target. A good array is an array where the number of different integers in that array is exactly k. com/cppnutsCOMPLETE PLAYLIST Jan 7, 2021 · Welcome to Subscribe On Youtube 1865. Note: This is an excellent problem to learn problem solving using two pointers and hash table. Example: Approach: Naive approach to run the nested loops and add each pair to check it with the given sum. May 5, 2018 · Given an array of distinct integer values, count the number of pairs of integers that have difference k. Otherwise, return false. Mar 28, 2023 · Given an array arr [] of size N. Find pairs with the given sum in an array. Codeforces. Find pairs Mar 18, 2025 · Given an array arr[] of positive integers and an integer target, determine if there exist two distinct indices such that the sum of their corresponding elements equals the target. Dec 30, 2014 · Given an array of integers find the number of all ordered pairs of elements in the array whose sum lies in a given range [a,b] Here is an O(n^2) solution for the same ''' counts all pairs in ar Jul 23, 2025 · We can also solve this problem using binary search. Count the number of pairs whose sum exists in the given array. Let's findTotalWays (arr, i, s, target) tells us number of ways to reach target, if first i Keep storing the numbers in a hashset as you move through the array. Give the algorithm. Understand the brute force and hash table approaches. A subarray is a contiguous non-empty sequence of elements within an array. The idea is to sort the array and for each number, we calculate its complement ( target - current number ) and then use binary search to check if the complement exists in the remaining elements of the array. Formally, sum (arri + arrj) + 1 = sum (arri1 + arrj1). Nov 13, 2024 · Defining the countpairs Function: The countpairs function is defined to count the number of pairs whose sum is less than or equal to a given limit. We have to pair the integers such that each integer should be in exactly one pair and each sum of pairs is consecutive and distinct. You are tasked to implement a data structure that supports queries of two types: Add a positive integer to an element of a given index in the array nums2. func checkPairs(in numbers: [Int], forSum target: Int) -> String { for (i, x) in numbers. Max Pair Sum in an Array - You are given an integer array nums. If it is not possible to find the pairs return -1. Examples: Input: arr [] = [1, 5, 3, 2] Output: 2 Explanation: In the given array, there are two such triplets such that sum of the two numbers is equal to the third number, those are (1, 2, 3), (3, 2, 5) Input: arr [] = [3, 2, 7 Subarrays with K Different Integers - Given an integer array nums and an integer k, return the number of good subarrays of nums. length Jun 4, 2019 · For example, I am provided an array: 1, 3, 9, 6, 5, 8, 3, 4 The problem is that I have to find pairs whose sum is 9 in the array mentioned above. Jul 6, 2022 · Given an array of distinct positive integers and a number x, find the number of pairs of integers in the array whose XOR is equal to x. We can return triplets in any order, but all the returned triplets should be internally sorted, i. The time complexity of this approach is O (N 2). Count the number of pairs (i, j) such that nums1[i] + nums2[j] equals a given value (0 <= i < nums1. May 31, 2024 · Learn how to solve the Two Sum problem efficiently. Brute force approaches will take O(N^2) time but we can solve this in O(N) time using a Hash Map. e. Jul 11, 2025 · Given an array a r r arr of distinct elements, the task is to find the total number of two element pairs from the array whose sum is a perfect square. JOIN ME—————YouTube 🎬 https://www. Aug 6, 2025 · The very basic approach is to generate all the possible pairs and check if any pair exists whose sum is equals to given target value, then increment the count variable. By calling this function twice with different . Intuitions, example walk through, and complexity analysis. Eg : (2, 1) and (1, 2) will be considered as only one pair. So in our map, 40 points to 0. Examples : Input : arr[] = {2, 8, 7, 1, 5}; Output : 2 5 7 1 Input : arr[] = {7, 8, 5, 9, 11}; Output : Not Exist A Naive Approach is to run three loops to find pair whose sum exists in an array. , target - arr [i]) and perform binary search on the remaining subarray (from index i+1 to end) to find that complement. Jul 23, 2025 · Given an array arr [] of size n, which is sorted and then rotated around an unknown pivot, the task is to check whether there exists a pair of elements in the array whose sum is equal to a given target value. 2. Jul 23, 2025 · Given an array of n distinct and positive elements, the task is to find pair whose sum already exists in the given array. And we can’t make a pair using same position element. If the sum is equal to target, return true. Jul 11, 2025 · The stepwise algorithm is: Find x = arr [i]%k. We can return pairs in any order, but all the returned pairs should be internally sorted, that is for any pair(i, j), i should be less than j. Examples: Input: arr [] = {2, 3, 6, 9, 10, 20} Output: 2 Only possible pairs are (3, 6) and (6, 10) Input: arr [] = {9, 2, 5, 1} Output: 0 Naive Approach: Use nested loops and check every possible pair for whether their sum is a perfect square Jul 4, 2024 · Suppose A = [a_1, , a_n] is an array of distinct integers and k is a given integer. Total possible unique sums would be equal to the size of unordered_set. GeeksforGeeks | A computer science portal for geeks Mar 2, 2021 · I am trying to find all pairs in an array with sum equal to k. Count the Number of Good Subarrays - Given an integer array nums and an integer k, return the number of good subarrays of nums. Time Complexity: O (N 2) Better approach is to use the Map. A={1,2,3,5,6} Sum=6 then answer should be {1,2,3} {1,5} {6} Presently I can think of two ways of doing this, Use Recursion ( which I suppose should be last thing to consider for an interview question) In this tutorial, I have explained how to find pairs in array with given sum. So return the size of the unordered set. The value of |x| is defined as: * x if x >= 0. * -x if x < 0. Examples: Input: arr [] = {5, 1, 2}, L = 4, R = 7 Output: 2 Explanation: The pairs satisfying the necessary conditions are as follows: (5, 1): Sum = 5 + 1 = 6, which lies in the range [4, 7]. Then we need to pair this element with all the elements in the array from index 0 to N-1. Jun 17, 2021 · Given an array of n integers and a number targetSum, check whether there is a pair of elements in the array that sums to exactly targetSum. , for any triplet [q1, q2, q3], the condition q1 ≤ q2 ≤ q3 should hold. If sum < target, we move the left pointer towards right. Arrays are really important because we are going to use them a lot in future topics. Contrary to the earlier comment, this is the same problem as pairs which add up to d. sort ()) for ordered access. Learn how to count the number of distinct pairs whose sum exists in a given array using C++. May 1, 2016 · When I see the number 10 in index 0, I make a note that if I ever find a 40 (50 - 10 = 40) in this list, then I can find its pair in index 0. In this video, we'll are going to solve some more questions of the array. Print the pairs of integers satisfying all the conditions. Mar 10, 2024 · Problem Formulation: We aim to identify all the unique pairs of numbers within a given array where the absolute difference between them is a specific value k. Below is the implementation of the above approach: Jul 12, 2025 · Given an array of distinct positive integers arr [] of length n, the task is to count all the triplets such that the sum of two elements equals the third element. While repeating pairs will not be counted again. Mar 16, 2021 · Learn how to find pairs in an array whose sums already exist in the same array using C++. The problem emphasizes understanding array manipulation and optimizing search operations through hashing. Feb 17, 2020 · Given an integer array and a positive integer k, count all distinct pairs with difference equal to k. Finding Pairs With a Certain Sum Description You are given two integer arrays nums1 and nums2. A subarray arr is good if there are at least k pairs of indices (i, j) such that i < j and arr [i] == arr [j]. Assume that all elements are distinct. Better than official and forum solutions. However, the pair must not be repetitive. In other words, we need to check for a pair of elements in the array that sum exactly to the target value. So make sure that you watch this Mar 11, 2012 · Space complexity is O (1). youtube. Count the number of pairs (i, j) such that nums1[i] + nums2[j] equals a given value (0 &lt;= i &lt; nums1 Can you solve this real interview question? Finding Pairs With a Certain Sum - You are given two integer arrays nums1 and nums2. You are tasked to implement a data structure that supports queries of two types: 1. Examples, code solutions in Python & Java. (Single traversal is required) In the next traversal, for every element check if it can be combined with any other element (other than itself!) to give the desired sum. Then for each element, we compute the required complement (i. Jul 23, 2025 · The idea is to sort the array and use two pointers at the beginning and end of the array. The same number may be chosen from candidates an unlimited number of times. Jul 23, 2025 · Efficient solution - A better solution is possible in O (n) time. Note: 1. This continues until all pairs are checked, giving us all the distinct pairs. I implement a solution but it returns only the first pair that it finds. **def countpairs (x,length,sum): count = 0 for Sep 15, 2025 · Given an unsorted integer array, find a pair with the given sum in it There are several methods to solve this problem using brute-force, sorting, and hashing. Return the maximum sum or -1 if no such pair exists. The hash set method is best for speed, while the two-pointer method is best for reducing memory usage. Solve using two methods: hashing and brute force. Two Pointers on a sorted array to count all pairs with sum ≤ target in O (n), then use subtraction to get the [lower, upper] range. Jul 31, 2022 · Given an array of N integers, and an integer K, find the number of pairs of elements in the array whose sum is equal to K. Step By Step Implementation: Sort the array in non-decreasing order. Feb 18, 2021 · You are given an array/list ‘ARR’ consisting of ‘N’ distinct integers arranged in ascending order. Mar 15, 2021 · Using the frequency array, we can easily find pairs in ascending order which have a target sum of say T. Below is the implementation of the above approach: Objective: Given an array of integers, write a program to count all the pairs with the given sum. The goal is to find two distinct elements from A whose sum is exactly k, or report that no such elements exist. * For example, [1,2,3,1,2] has 3 different integers: 1, 2, and 3. Dec 30, 2016 · The complementaries array is used just for keeping track of the numbers needed for making the sum. < numbers. K diff Pairs in an Array | Leetcode 532 | Arrays Ayushi Sharma 48. You are given an array of integers a and an integer k. Two Sum - Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. We will find out how we can count the number of pairs in an array whose sum is equal to a certain number. I want a solution less then this. Combination Sum - Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. For eg. 4K subscribers 300 Jul 12, 2025 · The very basic approach is to generate all the possible pairs and check if any pair exists whose sum is equals to given target value, then increment the count variable. You are also given an integer ‘TARGET’. Jul 23, 2025 · Given an array arr [] consisting of N integers and two integers L and R, the task is to count the number of pairs whose sum lies in the range [L, R]. #arrays #coding #programming #competitiveprogramming #coding #dsa Hey, Guys in this video I have explained how we can solve the problem 'Count pairs with given sum'. Complete the function pairSum () to get the expected output. Can you solve this real interview question? Count Array Pairs Divisible by K - Given a 0-indexed integer array nums of length n and an integer k, return the number of pairs (i, j) such that: * 0 <= i < j <= n - 1 and * nums [i] * nums [j] is divisible by k. Given an array of N positive integers. Aug 3, 2024 · Given an array of N integers, and an integer K, find the number of pairs of elements in the array whose sum is equal to K. Sep 30, 2024 · We have given an array of integers and a value, We had to find if there is a triplet in the array whose sum is equal to the given value. This is the solution by Geeks for Geeks: // C++ implementation of s Nov 23, 2015 · I just had an online coding interview and one of the questions asked there is for a given array of integers, find out the number of pairs whose summation is equal to a certain number (passed as parameter inside the method ). Sep 25, 2020 · Given n integers, produce pairs which sum to a number evenly divisible by d. If radix sort is used, complexities of the whole algorithm are the same. You may assume that each input would have exactly one solution, and you may not use the same element twice. Examples: Input: N = 6, arr [] = {2, 3, 1, 4, 6, 5} Output: 1 6 3 Oct 11, 2018 · Given an array of integers, and a number ‘sum’, find the number of pairs of integers in the array whose sum is equal to ‘sum’. For instance, given the input array [1, 5, 3, 4, 2] and a difference value k = 3, the desired output would be a list of pairs such as [(1, 4), (2, 5)], where each pair differs by 3. Jan 8, 2024 · A quick look at several algorithms for finding pairs of numbers in an array that add up to a given sum in Java using traditional for loops and the Java 8 Stream API. Design an algorithm to find all pairs of integers within an array which sum to a specified value. The hash-based approach offers a significant improvement in performance over the brute-force method, making it a go-to solution for this type of problem. If sum > target, we move the right pointer towards left. 2ubj mqv p8 o7m aq8zy 5ysn0 4hish0 zeym 33edx bwpu