Can you solve this real interview question? Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. The Core Equation Most problems boil down to: prefixSum [R] - prefixSum [L] = K. That's the essence of the Subarray Sum Equals K problem. Subarrays must be continuous portions of the original array, and May 1, 2025 · Subarray Sum Equals K - LeetCode 560 - Python #leetcode Deepti Talesra 16. Core Idea: The Sliding Window Imagine two pointers, left and right , forming the boundaries of a "window" over the array. Return the length of the shortest subarray of the array infinite_nums with a sum equal to target. Given an array arr[] containing integers and an integer k, your task is to find the length of the longest subarray where the sum of its elements is equal to the given value k. kienonline19 / subarray_prefix_sum_sliding_window_questions. com/problems/subarray-sum-equals-k/ Bug Category Editorial Bug Description no bug Subarray sum equals k (with negatives). Given an array A[] of n integer elements, find the length of the longest subarray with sum equals to 0. Return the minimum number of operations such that the sum of each subarray of length k is equal. Master this DSA concept with hints and solutions. Nov 25, 2024 · Subarray Sum Equals K — Solution and Explanation Problem Statement Given an array of integers nums and an integer k, we need to return the total number of subarrays whose sum equals to k. Example 1: Input: nums = [1,2], k = 1 Output: 3 Explanation: The subarray [1, 2] with sum 3 has length equal to 2 which is divisible by 1 This video is part of the Prefix Sum Pattern series for coding interviews. Subarray Sum Equals K in Python, Java, C++ and more. 06M subscribers Jul 23, 2025 · The idea is to use a sliding window approach with two pointers to efficiently count the number of subarrays with sum equal to k. #Day20 – Solving Subarray Sum Equals K (LeetCode) Today, I worked on the Subarray Sum Equals K problem in C++ and learned why a simple running-sum approach is not enough. Practice Target Sum Patterns with 3 curated questions: Easy, Medium, and Hard. The simplest approach is to consider every possible subarray and check if its sum equals k. Example 1: Input: nums = [1,1,1], k = 2 Output: 2 Note: The length of the array is in range [1, 20,000]. Jul 28, 2025 · If you take a closer look at this problem, this is mainly an extension of Subarray with given sum. Provide an O (n) solution. Jan 25, 2025 · For subarray problem with stricter constraints like the one given in this question "subarray sum equals k", sliding window pattern cannot be applied because they violate the window expansion/contraction constraints. Finally, we return the count which keeps track of the number of subarrays with a sum equal to k. 05M subscribers Subscribed Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. 1 day ago · The most direct solution is to compute every subarray sum. If at any point the cumulative sum equals the given sum, then return starting and ending indices (1-based). A subarray is a contiguous collection of elements in an array, making this problem a great application of iterative search techniques as well as more complex prefix sum algorithms. Ace your Software Engineering interviews. We solve the Subarray Sum Equals K problem using an optimized Prefix Sum approach. Jun 12, 2017 · Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. Problem Description: Given an array containing N positive integers and an integer K. A **queen** in a chessboard can attack horizontally, vertically, and diagonally. Core Concepts: - How does event‑driven It then iterates through the array to find subarrays with a sum equal to k, and the nested loop helps in calculating the sum of various subarray ranges. A subarray is a contiguous part of an array. Subarray Sum Equals K You are given an array of integers `nums` and an integer `k`, return the total number of subarrays whose sum equals to `k`. **Example 1:** ```java Input: nums = [2,-1,1,2], k = 2 Output: 4 ``` Explanation: `[2]`, `[2,-1,1]`, `[-1,1,2]`, `[2]` are the subarrays whose sum is Jul 1, 2024 · 100 Days of Leetcode :Day 2 — Solving the Subarray Sum Equals K Problem (LC 560) Today, we’re diving into an interesting problem that will test our understanding of arrays and prefix sums. sum_map = {0: 1} # Initialize with 0 sum having count 1 for num in nums: . Leetcode 51. - Explain the difference between REST and GraphQL. 2 days ago · Can you solve this real interview question? Maximum Subarray Sum With Length Divisible by K - You are given an array of integers nums and an integer k. Example 1: Input: arr = [1,4,1,3], k = 2 Output: 1 Explanation: we can do one operation on index 1 to make its value equal to 3. Subarray Sum Equals K Leetcode Solution Subarray Sum Equals K Leetcode Problem : Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. If it asks for the Maximum Subarray Sum, use Kadane’s Algorithm. The cost is the problem. Formally, the task is to find indices and with , such that the sum Here’s how smart problem-solvers think 👇 🔹 Sliding Window When to use: subarray / substring, contiguous elements, max/min/count/sum Clue words: subarray, substring, window, consecutive LeetCode 560: Subarray Sum = K - Prefix HashMap O (n) Genius! 📊🚀😊👍 #Description LeetCode 560 Subarray Sum Equals K! Prefix sums + HashMap = O (n). The number of such subarrays is equal to the frequency of (currSum - k). Jul 28, 2025 · If currSum is equal to k, we’ve found a valid subarray from index 0 to i. Examples : Input: nums = [0 Can you solve this real interview question? Minimum Size Subarray in Infinite Array - You are given a 0-indexed array nums and an integer target. Examples Example 1: Input: nums = Find subarrays with target sum using prefix sum and hash map technique with interactive examples. If there’s a prefix sum such that currSum - k exists in the map, then we’ve found subarrays ending at i with sum k. E Master the subarray sum equals K problem with efficient techniques and practical coding examples. Below are the main points to consider in your implementation. It can be solved in time and space. Example 1 In-depth solution and explanation for LeetCode 560. - Given an array of integers, return the longest subarray whose sum equals k. curr_sum = 0 . May 22, 2025 · To check this, we go k amount backwards by subtracting the amount 'k' from the currentPrefixSum. This problem requires several subarrays with sum k where k is the given target. Examples: 🚀 DSA Journey – Day 108: Longest Subarray with Given Sum K (Positive Numbers) Today I revisited a classic sliding window problem that works perfectly when the array contains only positive Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. The algorithm works by intelligently adjusting this window: Jan 11, 2025 · If current prefix sum - k is present in the hash table and is mapped to index j, then subarray from j to current index has sum equal to k. You’ll use it in many other problems, like longest subarray with sum at most k, or longest subarray with equal number of zeros and ones after transformation. If there is no such subarray, return 0 instead. You pick a start index i, then expand j to the right and track the running sum. A subarray is a contiguous non-empty sequence of elements within an array. md Created 2 minutes ago Star 0 0 Fork 0 0 Split Unified In computer science, the maximum sum subarray problem, also known as the maximum segment sum problem, is the task of finding a contiguous subarray with the largest sum, within a given one-dimensional array A [1n] of numbers. Time Complexity: O (n) Space Complexity: O (1) The sliding window technique is incredibly efficient for subarray problems. Return the maximum sum of a subarray of nums, such that the size of the subarray is divisible by k. Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. Note that: * A subarray is a contiguous part of the array. The article provides a comprehensive guide on solving the "Subarray Sum Equals K" problem, highlighting the importance of efficient algorithms like Kadane's and prefix sums for identifying contiguous subarrays that sum to a given integer k. Oct 27, 2024 · Let’s dive into one of the more interesting algorithm problems, Subarray Sum Equals K. This is the best place to expand your knowledge and get prepared for your next interview. Jan 13, 2026 · I recommend you treat this as a mental template: prefix sum + earliest index stored in a hash map. This subtracted value is the complementPrefixSum. Established a set (2-3) of test cases to verify their own solution later. If there is no subarray with sum equal to k, return 0. Better than official and forum solutions. 🔍 Key Learnings Master DSA, Coding Interview Patterns and System Design. Illustration: Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. Can you solve this real interview question? Maximum Size Subarray Sum Equals k - Level up your coding skills and quickly land a job. The Subarray Sum Equals K problem involves finding the number of subarrays in a given array whose elements add up to a number K. Binary Subarrays With Sum - Given a binary array nums and an integer goal, return the number of non-empty subarrays with a sum goal. Jul 23, 2025 · For each starting element, the inner loop iterates through subsequent elements and adding each element to the cumulative sum until the given sum is found or the end of the array is reached. The key insight is that if we have a prefix sum s at current position and we previously had a prefix sum of s - k at some earlier position, then the subarray between those two positions has a sum of exactly k. Struggling with the Subarray Sum Equals K problem on LeetCode (560)? In this video, I provide a step-by-step explanation of the solution using the prefix sum and hash map technique. Subarray Sum Equals K | Brute-Better-Optimal approach Auto-dubbed Apna College 7. If there is no such subarray return -1. Maximum Size Subarray Sum Equals k in Python, Java, C++ and more. curr_sum += num. The time complexity of this solution is improved compared to the brute-force approach. Problem Description Given an array of integer nums and an integer k, return the total number of continuous subarrays whose sum equals k. 3K subscribers Subscribe Dec 8, 2023 · What is the Subarray Sum Equals K Problem? One particular problem that frequently arises is finding subarrays whose sum equals a given number, commonly referred to as the “subarray sum equals k” problem. If no such sub-array exists, return 0. . A subarray is a contiguous part of the array. for every index in the input array consider the index as i index of a sub array for each i index Loop through the array from i index to n - 1 using index j Add nums[j] to sum if sum == k, increment count after both loops complete, return count. N Queens The **n-queens** puzzle is the problem of placing `n` queens on an `n x n` chessboard so that no two queens can attack each other. Count Subarray sum Equals K | Brute - Better -Optimal take U forward 965K subscribers Subscribed Detailed solution for Longest Subarray with given Sum K (Positives) - Problem Statement: Given an array nums of size n and an integer k, find the length of the longest sub-array that sums to k. When would you pick one over the other? - Write a SQL query to fetch the top 3 departments by average salary, including the average value. Given an array of integers arr (can include negatives) and an integer k, return the number of contiguous subarrays with sum exactly k. Dec 25, 2024 · 560. huahua LeetCode algorithm data structure solution Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. This is clean and easy to verify, and I still use it for quick sanity checks on tiny inputs or during interviews to build intuition. Detailed solution for Count Subarray sum Equals K - Problem Statement: Given an array of integers and an integer k, return the total number of subarrays whose sum equals k. When the sum equals k, calculate the window length and update the maximum. A … LeetCode Solutions in C++23, Java, Python, MySQL, and TypeScript. 🔹Interview Gold: The "Cheat Sheet" 1. count = 0 . What is Subarray Sum? The subarray sum is the sum of elements in a subarray. Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. A **subarray** is a contiguous **non-empty** sequence of elements within an array. 和为 K 的子数组 - 给你一个整数数组 nums 和一个整数 k ，请你统计并返回 该数组中和为 k 的子数组的个数 。 子数组是数组中元素的连续非空序列。 Sep 26, 2024 · In the “Subarray Sum Equals K” problem, the goal is to find the number of continuous subarrays that sum up to a given value, k. Established a set (1-2) of edge 4 days ago · LeetCode Username Sivaram_naidu Problem Number, Title, and Link https://leetcode. You will learn how to find the number of continuous subarrays whose sum is exactly equal to K, a Unit 10 Session 2 (Click for link to problem statements) Problem Highlights 💡 Difficulty: Medium ⏰ Time to complete: 30 mins 🛠️ Topics: Array, Hashing, Prefix Sum 1: U-nderstand Understand what the interviewer is asking for by using test cases and questions about the problem. Subarray Sum Equals K — LeetCode Medium Problem — Full Solution and approach explained Problem Statement Given an array of integers nums and an integer k, return the total number of … May 22, 2025 · Algorithm: Initialize a variable count = 0 to keep track of the number of subarrays with sum equal to k. If the sum equals k, you update the maximum length. Can you solve this real interview question? Subarray Sums Divisible by K - Given an integer array nums and an integer k, return the number of non-empty subarrays that have a sum divisible by k. In-depth solution and explanation for LeetCode 325. Your task is to find the length of the longest Sub-Array with sum of the elements equal to the given value K. Can you solve this real interview question? Minimum Size Subarray Sum - Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. Nov 29, 2020 · Problem Description: Given an array containing N positive integers and an integer K. 𝐎𝐩𝐭𝐢𝐦𝐚𝐥 𝐒𝐨𝐥𝐮𝐭𝐢𝐨𝐧: Using a Hash Table (Map In this video, we solve an important TCS NQT programming question: Subarray Sum Equals K. Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals k. Nov 12, 2021 · Whenever we find a subarray with a sum equal to k, we increment our counter by 1. For each starting index, we extend the subarray element by element, maintaining a running sum. Each solution contains a unique board layout where the queen pieces are placed Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. A 0-indexed array infinite_nums is generated by infinitely appending the elements of nums to itself. A good subarray is a subarray where: * its length is at least two, and * the sum of the elements of the subarray is a multiple of k. The key insight is that we can find subarrays with sum exactly equal to k by calculating the difference between the count of subarrays with sum at most k and the count of subarrays with sum at most k-1. At first glance, it looks simple: given an array of integers, you’re tasked with finding subarrays that Subarray Sum Equals K - Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. Jun 7, 2020 · Number of subarrays having sum exactly equal to K This article would help you understand how two problems which seem so similar can have different approaches depending on the allowed input. complementPrefixSum is a number that is 'k' less than the currentPrefixSum in the prefixsum array. Record currSum in the map to help future matches. Intuitions, example walk through, and complexity analysis. Aug 25, 2024 · Imagine you have a list of numbers, and you want to find out how many times a specific total, let's call it K, can be made by adding up some consecutive numbers in the list. Each solution contains a unique board layout where the queen pieces are placed 560. Given an integer `n`, return all distinct solutions to the **n-queens puzzle**. Problem Statement Given an array of positive integers and a target sum K , find the length of the longest contiguous subarray whose elements sum up to K . You are given an array of integers `nums` and an integer `k`, return the total number of subarrays whose sum equals to `k`. Continuous Subarray Sum - Given an integer array nums and an integer k, return true if nums has a good subarray or false otherwise. Leetcode 560. Example 1: Subarray Sum Equals K - Prefix Sums - Leetcode 560 - Python NeetCode 1. To count subarrays with sum k, we use a hash map to store the frequency of prefix sums. The range of numbers in the array is [-1000, 1000] and the range of the integer k is [-1e7, 1e7]. Problem restatement and constraints that matter If the difference between the current prefix sum and k has appeared before, it means a valid subarray exists.

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