Leetcode 560. Subarray Sum Equals K

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 to k.

Example 1:

Input:nums = [1,1,1], k = 2 Output: 2

Note:

The length of the array is in range [1, 20,000].The range of numbers in the array is [-1000, 1000] and the range of the integer k is [-1e7, 1e7].

思路： （待补充）

class Solution { public int subarraySum(int[] nums, int k) { HashMap<Integer, Integer> map = new HashMap(); map.put(0, 1); int sum = 0; int result = 0; for(int i = 0; i < nums.length; i++) { sum += nums[i]; if(map.containsKey(sum - k)) { result += map.get(sum-k); } map.put(sum, map.getOrDefault(sum, 0) + 1); } return result; } }