Submission #72533387

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Source Code Expand

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

ll op(ll a, ll b){
    return a+b;
}
ll e(){return 0;}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; string s; cin >> n >> s;
    vi a(n+1, 0);
    rep(i, n){
        if(s[i] == 'A'){
            a[i+1] = a[i]+1;
        }else if(s[i] == 'B'){
            a[i+1] = a[i]-1;
        }else{
            a[i+1] = a[i];
        }
    }
    ll ans = 0;
    segtree<ll, op, e> seg(1000010);
    seg.set(500005, 1);
    rep2(i, 1, n+1){
        ll c = 500005+a[i];
        ans += seg.prod(0, c);
        seg.set(c, seg.get(c)+1);
    }cout << ans << endl;

    return 0;
}

Submission Info

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