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].
注意一些特殊情况,(会对代码的顺序有一点影响)
sum == k
k == 0
class Solution { public int subarraySum(int[] nums, int k) { Map<Integer, Integer> map = new HashMap<>(); int count = 0; int sum = 0; map.put(0, 1); for (int i = 0; i < nums.length; i++) { sum += nums[i]; if (map.containsKey(sum - k)) { count += map.get(sum - k); } map.put(sum, map.getOrDefault(sum, 0) + 1); } return count; } }
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