leetcode 930. Binary Subarrays With Sum
This remains me of some 'subarray count' type problems…..
class Solution {
public int numSubarraysWithSum(int[] A, int S) {
int[] ps = new int[A.length + 1];
ps[0] = 1;
int sum = 0;
int ret = 0;
for (int v: A) {
sum += v;
if (sum - S >= 0) {
ret += ps[sum - S];
}
ps[sum] += 1;
}
return ret;
}
}