各个元素之和等于给定值的连续子数组的个数

 1 private int getNumOfSubThatSumIsTarget(int[] arr, int target) {
 2     Map<Integer, Integer> map = new HashMap<>();
 3     map.put(0, 1);
 4     
 5     int result = 0;
 6     int curSum = 0;
 7     for (int i = 0; i < arr.length; ++i) {
 8         curSum += arr[i];
 9         
10         result += map.getOrDefault(curSum - target, 0);
11         
12         map.put(curSum, map.getOrDefault(curSum, 0) + 1);
13     }
14     
15     return result;
16 }