Submission #149230

#	Time	Username	Problem	Language	Result	Execution time	Memory
149230		anonymous	Race (IOI11_race)	C++14	100 / 100	755 ms	97144 KiB

race

#include<iostream>
#include<tr1/unordered_map>
#include<utility>
#include<vector>
#include "race.h"
using namespace std;
int N,ui,vi,wi;
long long K;
int big[200005],out=1<<30;
vector <pair<int,int> > adj[200005];
tr1::unordered_map<long long,int>  M[200005];
int dfs(int u, int prev, long long depth, int e) {
    big[u]=u;
    M[u][depth]=e;
    for (auto v: adj[u]) {
        if (v.first == prev) {continue;}
        int res=dfs(v.first,u,depth+v.second,e+1);
        if (M[big[u]].size()<M[res].size()) {
            swap(big[u],res);
        }
        for (auto val: M[res]) {
            if (M[big[u]].find(K+2*depth-val.first) != M[big[u]].end()) {
                out=min(out,M[big[u]][K+2*depth-val.first]+val.second-2*e);
            }
        }
        for (auto val: M[res]) {
            if (M[big[u]].find(val.first)==M[big[u]].end()) {
                M[big[u]][val.first]=val.second;
            } if (M[big[u]][val.first]>val.second) {
                M[big[u]][val.first]=val.second;
            }
        }
    }
    return(big[u]);
}

int best_path(int n, int k, int H[][2], int L[]) {
    K=k;
    for (int i=0; i<n-1; i++) {
        adj[H[i][0]].push_back({H[i][1],L[i]});
        adj[H[i][1]].push_back({H[i][0],L[i]});
    } //1 indexify
    dfs(0,-1,0,0);
    return(out<=n ? out : -1);
}

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