Submission #412491

#	Time	Username	Problem	Language	Result	Execution time	Memory
412491		jeqcho	Race (IOI11_race)	C++17	9 / 100	344 ms	262148 KiB

race

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

typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fi first
#define se second

int const n=2e5+3;
int const k_=1e2+3;
pair<int,pii> dp[n][k_];
vpi adj[n];
int const INF=1e9;
int mn=INF;

void dfs(int now, int par, int k)
{
	F0R(i,k+1)
	{
		dp[now][i]={INF,pii{-1,-1}};
	}
	dp[now][0].fi=0;
	dp[now][0].se.fi=now;
	trav(chi,adj[now])
	{
		if(chi.fi==par)continue;
		dfs(chi.fi,now,k);
		F0R(i,k+1)
		{
			if(i-chi.se<0)continue;
			if(dp[chi.fi][i-chi.se].fi+1 == dp[now][i].fi)
			{
				dp[now][i].se.se=chi.fi;
			}
			else if(dp[chi.fi][i-chi.se].fi+1 < dp[now][i].fi)
			{
				dp[now][i] = {dp[chi.fi][i-chi.se].fi+1, pii{chi.fi,-1}};
			}
		}
	}
	F0R(i,k+1)
	{
		if(dp[now][i].se.fi==-1)continue;
		if(dp[now][k-i].se.fi==-1)continue;
		if(dp[now][i].se.fi==dp[now][k-i].se.fi)
		{
			if(dp[now][i].se.se==-1&&dp[now][k-i].se.se==-1)continue;
		}
		mn=min(mn,dp[now][i].fi+dp[now][k-i].fi);
	}
}

int best_path(int N, int K, int H[][2], int L[]){
	F0R(i,N-1)
	{
		int u = H[i][0];
		int v = H[i][1];
		adj[u].pb({v,L[i]});
		adj[v].pb({u,L[i]});
	}
	dfs(0,-1,K);
	if(mn>=INF)return -1;
	return mn;
}

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