Submission #467835

#	Time	Username	Problem	Language	Result	Execution time	Memory
467835		nickmet2004	Election (BOI18_election)	C++11	100 / 100	1454 ms	29908 KiB

election

#include<bits/stdc++.h>

using namespace std;
const int N = 5e5 + 5;
int n , a[N];
string s;
struct Node{
    int L , R , cnt , ans;
    Node operator+(Node y){
        Node ret;
        ret.cnt = cnt + y.cnt;
        ret.L = max(L , cnt + y.L);
        ret.R = max(y.R , y.cnt + R);
        ret.ans = max({L + y.R , cnt + y.ans , ans + y.cnt});
        return ret;
    }
}T[4*N];
void B(int l = 0 , int r= n - 1 , int pos= 0){
    if(l == r){
        if(a[l] == 1) T[pos] = {1 , 1 , 1 , 1};
        else T[pos] = {0 , 0 , -1 , 0};
        return;
    }
    int mid = (l + r) >> 1;
    B(l , mid , pos * 2 + 1);
    B(mid + 1 , r , pos * 2 + 2);
    T[pos] = T[pos * 2 + 1] + T[pos * 2 + 2];
}
Node get(int L , int R , int l =0 , int r= n - 1 ,int pos = 0){
    if(r <L || R < l) return {0 , 0 ,0 , 0};
    if(L <= l && r <= R) return T[pos];
    int mid = (l + r) >> 1;
    return get(L , R , l , mid  , pos * 2 + 1) + get(L , R , mid + 1 , r ,pos * 2 + 2);
}
int main (){
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> s;
    for(int i = 0; i < n; ++i){
        if(s[i] == 'T') a[i] = 1;
        else a[i] = -1;
    }
    B();
    int q;
    cin >> q;
    while(q--){
        int a, b;
        cin >> a >> b;--a; --b;
        cout << get(a , b).ans << endl;
    }
return 0;
}

• Subtask 1: 28 / 28
• Subtask 2: 54 / 54
• Subtask 3: 18 / 18