Submission #941254

#	Time	Username	Problem	Language	Result	Execution time	Memory
941254		NotLinux	Election (BOI18_election)	C++17	100 / 100	541 ms	81524 KiB

election

#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define int long long
struct Node {
    int sum, ans, pref, suf;
};
struct SegTree {
    int n;
    vector<Node> tree;
    vector<int> v;
 
    SegTree(vector<int> _v) {
        v = _v;
        n = sz(v);
        tree.resize(4*n+5);
        build(1, 0, n-1);
    }
 
    Node merge(Node a, Node b) {
        Node res;
 
        res.sum = a.sum + b.sum;
        res.pref = max({ (int)0, a.pref, a.sum + b.pref });
        res.suf = max({ (int)0, b.suf, b.sum + a.suf });
        res.ans = max({ a.pref + b.suf, a.ans + b.sum, a.sum + b.ans });
 
        return res;
    }
 
    void build(int u, int tl, int tr) {
        if(tl == tr) {
            tree[u].ans = max(v[tl], (int)0);
            tree[u].sum = v[tl];
            tree[u].pref = tree[u].suf = max(v[tl], (int)0);
        } else {
            int tm = (tl + tr) / 2;
            build(2*u, tl, tm);
            build(2*u+1, tm+1, tr);
            tree[u] = merge(tree[2*u], tree[2*u+1]);
        }
    }
 
    Node query(int u, int tl, int tr, int l, int r) {
        if(tl > tr || tl > r || l > tr) return Node{0, 0, 0, 0};
        if(l <= tl && tr <= r) return tree[u];
        int tm = (tl + tr) / 2;
        return merge(query(2*u, tl, tm, l, r),query(2*u+1, tm+1, tr, l, r));
    }
 
    int query(int l, int r) {
        return query(1, 0, n-1, l, r).ans;
    }
};
 
int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
 
    int n;
    cin >> n;
 
    vector<int> v(n);
    for(int i=0; i<n; i++) {
        char ch;
        cin >> ch;
        v[i] = (ch == 'T' ? 1 : -1);
    }
 
    SegTree tree(v);
    
    int q;
    cin >> q;
 
    while(q--) {
        int l, r;
        cin >> l >> r;
        cout << tree.query(l-1, r-1) << '\n';
    } 
}

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