hasing_number_of_subarray.cpp

#include <bits/stdc++.h>
using namespace  std;
#define vi vector<int>
#define pii pair<int,int>
#define vii vector<pii>
#define  rep(i,a,b) for(int i=a;i<b;i++)
#define ff first
#define ss second


int main(){

	int n;
	cin>>n;
	vi a(n);
	rep(i,0,n){
		cin>>a[i];
	}
	map<int,int> cnt;
	int presum=0;
	rep(i,0,n){
		presum+=a[i];
		cnt[presum]++;
	}
	int ans=0;
	map<int,int>:: iterator it;
	for(it=cnt.begin();it!=cnt.end();it++){

		int c=it->ss;
		ans+=(c*(c-1))/2;

		if(it->ff==0){
			ans+=it->ss;
		}
		

	}

	cout<<ans<<endl;

	return 0;
}