Binary Subarrays With Sum LeetCode solution in Java

1
class Solution {
2
public int numSubarraysWithSum(int[] nums, int goal) {
3

4
    int pre=0,cnt=0;
5
    HashMap<Integer,Integer> m=new HashMap();
6
    for(int i:nums){
7

8
        pre+=i;
9
     //   if(pre-goal<0)continue;
10
        if(pre-goal==0)cnt++;
11

12
        if(m.containsKey(pre-goal)){
13
            cnt+=m.get(pre-goal);
14

15

16
        }
17
        m.put(pre,m.getOrDefault(pre,0)+1);
18

19

20

21
    }
22

23
    return cnt;
24
}