Hi, So i tried to solve this problem . And i did understand the first part of the tutorialbut got a little confused at the end. It says that I have to add everything from cnt[0] to cnt[n-1] to get my answer. But to get a faster result they did a different workaround. They created sums[] and worked on it. This is the c++ solution. Now, why would they do this?:
for(int i = n-2 ; i >= 0 ; --i)
cnt[i] += cnt[i+1];
and in this :
for(int i = 0 ; i+2 < n ; ++i) {
ss += a[i];
if (ss == s)
ans += cnt[i+2];
}
Why i+2?.