Submission #1276426

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276426		mingga	Election (BOI18_election)	C++20	100 / 100	409 ms	36648 KiB

election

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 5e5 + 7;
int n, q;
int a[N];

struct Node {
	int lef, rig, tot, ans;
	Node() {
		lef = rig = tot = ans = 0;
	}
	Node(int x) {
		tot = x;
		lef = rig = ans = max(0, x);
	}
	Node operator + (const Node& o) {
		Node tmp;
		tmp.lef = max(lef, tot + o.lef);
		tmp.rig = max(o.rig, rig + o.tot);
		tmp.tot = tot + o.tot;
		tmp.ans = max({lef + o.rig, ans + o.tot, tot + o.ans});
		return tmp;
	}
} st[N * 4 + 4];

void build(int i = 1, int l = 1, int r = n) {
	if(l == r) {
		st[i] = Node(a[l]);
		return;
	}
	int m = (l + r) >> 1;
	build(i * 2, l, m);
	build(i * 2 + 1, m + 1, r);
	st[i] = st[i * 2] + st[i * 2 + 1];
}

Node get(int i, int l, int r, int u, int v) {
	if(l > v or r < u) return Node();
	if(u <= l and r <= v) return st[i];
	int m = (l + r) >> 1;
	return get(i * 2, l, m, u, v) + get(i * 2 + 1, m + 1, r, u, v);
}

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n;
	for(int i = 1; i <= n; i++) {
		char c; cin >> c;
		if(c == 'T') a[i] = 1;
		else a[i] = -1;
	}
	cin >> q;
	build();
	for(int i = 1; i <= q; i++) {
		int l, r; cin >> l >> r;
		cout << get(1, 1, n, l, r).ans << ln;
	}
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

election.cpp: In function 'int main()':
election.cpp:60:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
election.cpp:61:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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