제출 #166043

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
166043		errorgorn	경주 (Race) (IOI11_race)	C++14	100 / 100	585 ms	87600 KiB

race

#include "race.h"
#include <cstdio>
#include <set>
#include <vector>
#include <utility>
#include <algorithm>
using namespace std;
typedef pair<int,int> ii;

vector<ii> al[200005];
int offset[200005];
int offset2[200005];
set<ii> rope[200005];

int ans=1000000;

int k;

void dfs(int i,int p){
    rope[i].insert(ii(offset[i],offset2[i]));
    int target;
    set<ii>::iterator sit;

    for (auto it:al[i]){
        if (it.first==p) continue;
        offset[it.first]=offset[i]+it.second;
        offset2[it.first]=offset2[i]+1;

        dfs(it.first,i);
        if (rope[it.first].size()>rope[i].size()) swap(rope[it.first],rope[i]);

        for (auto x:rope[it.first]){
            target=k-x.first+offset[i]*2;
            sit=rope[i].lower_bound(ii(target,-1));
            if (sit==rope[i].end() || (*sit).first!=target) continue;

            ans=min(ans,(*sit).second+x.second-offset2[i]*2);
        }

        rope[i].insert(rope[it.first].begin(),rope[it.first].end());
    }
}

int best_path(int n, int K, int h[][2], int l[]){
    k=K;
    for (int x=0;x<n-1;x++){
        al[h[x][0]].push_back(ii(h[x][1],l[x]));
        al[h[x][1]].push_back(ii(h[x][0],l[x]));
    }

    dfs(0,-1);
    return (ans==1000000)?-1:ans;
}

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