Submission #399271

#	Time	Username	Problem	Language	Result	Execution time	Memory
399271		peuch	Roller Coaster Railroad (IOI16_railroad)	C++17	34 / 100	293 ms	15424 KiB

railroad

#include "railroad.h"
#include<bits/stdc++.h>
using namespace std;

const long long INF = 1e18;

int n;
vector<int> ord;
vector<int> S, T;

long long ans = 1e18;

long long dp[20][1<<18];
bool marc[20][1<<18];

long long getDP(int cur, int mask);
void bt(int i, long long sum);

long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
	S = s;
	T = t;
    n = s.size();
    ord = vector<int> (n);
	for(int i = 0; i < n; i++){
		ans = min(ans, getDP(i, (1 << n) - 1));
		ord[i] = i;	
	}
//	bt(0, 0);
	return ans;
}

long long getDP(int cur, int mask){
	if(marc[cur][mask]) return dp[cur][mask];
	marc[cur][mask] = 1;
	dp[cur][mask] = INF;
	if(!((1 << cur) & mask)) return dp[cur][mask] = INF;
	if(!((1 << cur) ^ mask)) return dp[cur][mask] = 0;
	for(int i = 0; i < n; i++)
		dp[cur][mask] = min(dp[cur][mask], getDP(i, mask ^ (1 << cur)) + max(0, T[i] - S[cur]));
	return dp[cur][mask];
}

void bt(int i, long long sum){
	if(sum > ans) return;
	if(i == n){
		ans = sum;
		return;
	}
	for(int j = i; j < n; j++){
		swap(ord[i], ord[j]);
		if(i != 0) sum += max(T[ord[i - 1]] - S[ord[i]], 0);
		bt(i + 1, sum);
		if(i != 0) sum -= max(T[ord[i - 1]] - S[ord[i]], 0);
		swap(ord[i], ord[j]);
	}
}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 0 / 30
• Subtask 4: 0 / 36