Submission #1268543

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268543		WH8	Crocodile's Underground City (IOI11_crocodile)	C++20	100 / 100	272 ms	45608 KiB

crocodile

#include "crocodile.h"
#include <bits/stdc++.h>
using namespace std;
#define s second
#define f first
#define pb push_back
int travel_plan(int N, int M, int R[][2], int L[], int K, int P[])
{
	vector<vector<pair<int,int>>> al(N);
	for(int i=0;i<M;i++){
		al[R[i][0]].pb({R[i][1], L[i]});
		al[R[i][1]].pb({R[i][0], L[i]});
	}
	vector<int> in(N, 0), dp(N, 1e9);
	priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> pq;
	// 2ndmin, index;

	vector<pair<int,int>> mn(N, {1e9, 1e9});
	for(int i=0;i<K;i++){
		in[P[i]]=1e9;
		dp[P[i]]=0;
		mn[P[i]]={0, 0};
		pq.push({0, P[i]});
	}
	auto upd = [&](int ind, int dist) -> bool {
		pair<int,int> bef=mn[ind];
		if(dist >= mn[ind].s) return 0;
		if(dist <= mn[ind].f){
			mn[ind].s=mn[ind].f;
			mn[ind].f=dist;
		}
		else {
			mn[ind].s=dist;
		}
		if(bef.s != mn[ind].s)return 1;
		return 0;
	};
	while(!pq.empty()){
		auto [smn, ind]=pq.top();pq.pop();
		if(mn[ind].s < smn) continue;
		for(auto [to, cost]:al[ind]){
			in[to]++;
			bool change = upd(to, mn[ind].s + cost);
			if(in[to]>=2 and change){ // we can push this guy
				pq.push({mn[to].s, to});
			}
		}	
	}
	return mn[0].s;
}

• Subtask 1: 46 / 46
• Subtask 2: 43 / 43
• Subtask 3: 11 / 11