CSES – Subarray Sums II

#include<bits/stdc++.h>
#define int long long
#define f first
#define s second
#define fastio ios_base::sync_with_stdio(0);cin.tie(0)
using namespace std;
int n,X;
vector<int> v;
map<int,int> sum;
signed main(){
    fastio;
    cin>>n>>X;
    for(int i=0;i<n;i++){
        int x; cin>>x;
        v.push_back(x);
    }
    int pre = 0, ans = 0;
    sum[0] = 1;
    for(int i : v){
        pre += i;
        ans += sum[pre-X];
        sum[pre]++;
    }
    cout<<ans<<"\n";
    return 0;
}