Submission #289349

#	Time	Username	Problem	Language	Result	Execution time	Memory
289349		Saboon	Shortcut (IOI16_shortcut)	C++17	31 / 100	2084 ms	512 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 10;
const ll inf = 1e18;
ll dp[maxn], pd[maxn], ap[maxn], ad[maxn], optL[maxn], optR[maxn];
ll ans[maxn], opt[maxn], tmp[maxn];
vector<int> l, d;
int c;
 
ll get(int L, int R){
	ll ret = max(ap[L],ad[R]);
	ll Cycle = c;
	for (int i = L; i < R; i++)
		Cycle += l[i];
	for (int i = L; i <= R; i++)
		tmp[i] = d[i];
	tmp[L] = dp[L], tmp[R] = pd[R];
	for (int i = L; i <= R; i++){
		ll now = 0;
		for (int j = i+1; j <= R; j++){
			now += l[j-1];
			ret = max(ret, min(now+tmp[i]+tmp[j],Cycle-now+tmp[i]+tmp[j]));
		}
	}
	return ret;
}
 
ll find_shortcut(int n, vector<int> l, vector<int> d, int c){
	::l = l, ::d = d, ::c = c;
	dp[0] = ap[0] = d[0];
	for (int i = 1; i < n; i++){
		ap[i] = max(ap[i-1], dp[i-1]+l[i-1]+d[i]);
		dp[i] = max(1LL*d[i], dp[i-1]+l[i-1]);
	}
	pd[n-1] = ad[n-1] = d[n-1];
	for (int i = n-2; i >= 0; i--){
		ad[i] = max(ad[i+1], pd[i+1]+l[i]+d[i]);
		pd[i] = max(1LL*d[i], pd[i+1]+l[i]);
	}
	ll answer = inf;
	for (int i = 0; i < n-1; i++){
		opt[i] = -1, ans[i] = inf;
		for (int j = i+1; j < n; j++){
			ll x = get(i,j);
			if (x < ans[i])
				ans[i] = x, optL[i] = j;
			if (x == ans[i])
				optR[i] = j;
		}
		answer = min(answer, ans[i]);
		for (int j = optL[i]; j <= optR[i]; j++)
			assert(get(i,j) == ans[i]);
	}
	return answer;
}

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