Submission #631862

#	Time	Username	Problem	Language	Result	Execution time	Memory
631862		czhang2718	Election (BOI18_election)	C++17	100 / 100	460 ms	28028 KiB

election

#include "bits/stdc++.h"
using namespace std;

const int N=5e5;
int n, q;
string s;

struct Node{
    int pre, suf, sum, ans;

    Node operator+(Node b){
        Node ret;
        ret.pre=max(pre, sum+b.pre);
        ret.suf=max(b.suf, b.sum+suf);
        ret.sum=sum+b.sum;
        ret.ans=max({ans+b.sum, b.ans+sum, pre+b.suf});
        return ret;
    }
} seg[4*N];

Node qry(int l, int r, int x=0, int lx=0, int rx=n){
    if(lx>=l && rx<=r) return seg[x];
    if(lx>=r || rx<=l) return {0, 0, 0, 0};
    int m=(lx+rx)/2;
    return qry(l, r, 2*x+1, lx, m)+qry(l, r, 2*x+2, m, rx);
}

void build(int x=0, int lx=0, int rx=n){
    if(rx-lx==1){
        if(s[lx]=='C') seg[x]={0, 0, -1, 0};
        else seg[x]={1, 1, 1, 1};
        return;
    }
    int m=(lx+rx)/2;
    build(2*x+1, lx, m);
    build(2*x+2, m, rx);
    seg[x]=seg[2*x+1]+seg[2*x+2];
    // cout << "seg[" << lx << " " << rx << "] " << seg[x].pre << " " << seg[x].suf << " " << seg[x].sum << " " << seg[x].ans << "\n";
}

int main(){
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> s;
    build();
    cin >> q;
    while(q--){
        int l,r; cin >> l >> r;
        cout << qry(l-1,r).ans << "\n";
    }
}

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