Submission #289430

#	Time	Username	Problem	Language	Result	Execution time	Memory
289430		Saboon	Shortcut (IOI16_shortcut)	C++17	0 / 100	1 ms	384 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];
ll ans[maxn], opt[maxn], tmp[maxn], far[maxn];
vector<int> l, d;
vector<ll> pos;
int c, n;

void init(){
	pos.push_back(0);
	for (int i = 0; i < n-1; i++)
		pos.push_back(pos.back()+l[i]);
}

ll getDis(int a, int b, int L, int R){
	ll Cycle = pos[R]-pos[L]+c;
	if (b < a)
		swap(a,b);
	ll ret = min(pos[b]-pos[a], Cycle-pos[b]+pos[a])+tmp[a]+tmp[b];
	return ret;
}
 
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];
	opt[L] = -1, far[L] = 0;
	for (int j = L+1; j <= R; j++){
		ll x = getDis(L, j, L, R);
		if (far[L] < x)
			far[L] = x, opt[L] = j;
	}
	for (int i = L+1; i <= R; i++){
		opt[i] = opt[i-1], far[i] = getDis(i, opt[i], L, R);
		while (true){
			int q = opt[i]+1;
			if (q == R+1)
				q = L;
			ll x = getDis(i, q, L, R);
			if (q != i and x >= far[i])
				far[i] = x, opt[i] = q;
			else
				break;
		}
	}
	for (int i = L; i <= R; i++)
		ret = max(ret, far[i]);
	return ret;
}
 
ll find_shortcut(int n, vector<int> l, vector<int> d, int c){
	::n = n, ::l = l, ::d = d, ::c = c;
	init();
	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; i++){
		ans[i] = inf;
		for (int j = i+1; j < n; j++){
			ans[i] = min(ans[i], get(i,j));
		}
		answer = min(answer, ans[i]);
	}
	return answer;
}

• 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