Submission #1020575

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020575		vjudge1	Shortcut (IOI16_shortcut)	C++17	0 / 100	2 ms	18780 KiB

shortcut

// #pragma once
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const ll INF = 1e18 + 100;
const int maxn = 1e6 + 100;
const int maxl = 20;

int n, C;
ll a[maxn];
int b[maxn];
ll p[2][maxl][maxn];
int lg[maxn];

ll get(int l, int r, int c){
	if(l > r) return -INF;
	int k = lg[r - l + 1];
	return max(p[c][k][l], p[c][k][r-(1<<k)+1]);
}

ll ans(int l, int r){
	if(l > r) return -INF;
	return get(l, r, 0) + get(l, r, 1);
}

bool ok(ll x){
	int tl = 0, tr = n + 1;
	while(tl < n && ans(1, tl+1) <= x) tl++;
	while(tr > 1 && ans(tr-1, n) <= x) tr--;
	for(int l = 1; l <= tl; l++){
		for(int r = max(l + 1, tr); r <= n; r++){
			if(ans(l+1, r-1) > x) continue;
			if(get(1, l, 0) + a[l] + get(r, n, 1) - a[r] + C > x) continue;
			if(get(tl+1, r-1, 0) + a[r] + C + get(1, l, 0) + a[l] > x) continue;
			if(get(l+1, tr-1, 1) - a[l] + C + get(r, n, 1) - a[r] > x) continue;
			return 1;
		}
	}
	return 0;
}

long long find_shortcut(int N, std::vector <int> l, std::vector <int> d, int c){
	n = N; C = c;
	for(int i = 1; i <= n; i++){
		b[i] = d[i-1];
		if(i == 1) continue;
		a[i] = a[i-1] + l[i - 2];
	}
	for(int i = 1; i <= n; i++){
		p[0][0][i] = b[i] - a[i];
		p[1][0][i] = b[i] + a[i];
		if(i > 1) lg[i] = lg[i >> 1] + 1;
	}
	for(int c = 0; c < 2; c++){
		for(int k = 1; k <= lg[n]; k++){
			for(int i = 1; i + (1<<k) - 1 <= n; i++){
				p[c][k][i] = max(p[c][k-1][i], p[c][k-1][i+(1<<(k-1))]);
			}
		}
	}
	ll res = ans(1, n);
	for(ll l = 0, r = res - 1; l <= r;){
		ll mid = (l + r) >> 1;
		if(!ok(mid)) l = mid + 1;
		else r = mid - 1, res = mid;
	}
	return res;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3