Submission #1005179

#	Time	Username	Problem	Language	Result	Execution time	Memory
1005179		Mardonbekhazratov	Race (IOI11_race)	C++17	21 / 100	3052 ms	11516 KiB

race

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include "race.h"
#include<vector>
#include<queue>
#include<array>

using namespace std;

int n,k,ans;
vector<vector<pair<int,int>>>v;

void dfs(int x,int p,long long dis,int cnt){
	if(dis>=k){
		if(dis==k) ans=min(ans,cnt);
		return;
	}
	for(auto [z,w]:v[x]){
		if(z!=p) dfs(z,x,dis+w,cnt+1);
	}
}

void solve(int x){
	queue<array<int,4>>q;
	q.push({x,x,0,0});
	while(!q.empty()){
		auto [x,p,dis,cnt]=q.front();
		q.pop();
		if(dis==k){
			ans=min(ans,cnt);
			continue;
		}
		for(auto [z,w]:v[x]){
			if(z!=p && dis+w<=k){
				q.push({z,x,dis+w,cnt+1});
			} 
		}
	}
}

int best_path(int N, int K, int H[][2], int L[]){
	n=N;
	k=K;
	vector<long long>pref(n);
	pref[0]=0;
	v.resize(n);
	bool sub1=true;
	for(int i=0;i<n-1;i++){
		v[H[i][0]].push_back({H[i][1],L[i]});
		v[H[i][1]].push_back({H[i][0],L[i]});
		pref[i+1]=pref[i]+L[i];
		if(H[i][0]!=i || H[i][1]!=i+1) sub1=false;
	}
	ans=n;
	if(sub1){
		for(int i=0;i<n-1;i++){
			auto pos=lower_bound(pref.begin(),pref.end(),pref[i]+K)-pref.begin();
			if(pos!=n && pref[pos]-pref[i]==K) ans=min(ans,(int)pos-i);
		}
		return (ans==n ? -1 : ans);
	}
	for(int i=0;i<n;i++){
		solve(i);
	}
	return (ans==n ? -1 : ans);
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57