제출 #970016

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
970016		lurhx	Race (IOI11_race)	C++17	0 / 100	3037 ms	2396 KiB

race

#include "race.h"

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
#define f first
#define s second
const int inf = 1e9;
vector<vector<pair<int,int>>> edges;
vector<bool> centroids;
vector<int> sizes;
int n,k;
int get_size(int node, int parent = -1) {
    int res = 1;
    for(auto i: edges[node]) {
        if(centroids[i.f] || i.f==parent)continue;
        res+=get_size(i.f,node);
    }
    return sizes[node]=res;
}
int get_centroid(int node,int parent = -1) {
    for(auto i: edges[node]) {
        if(centroids[i.f] || i.f == parent)continue;
        if(sizes[i.f]*2>n)
            return get_centroid(i.f,node);
    }
    return node;
}
map<int,int> dis1,dis2;
void dfs(int node,int val,int times,int parent = -1) {
    if(dis1.find(val)==dis1.end()) {
        dis1[val] = times;
    }else {
        if(dis2.find(val)==dis2.end())
            dis2[val] = times;
        else
            dis2[val] = min(dis2[val],times);
        if(dis2[val]<dis1[val])
            swap(dis2[val],dis1[val]);
    }
    for(auto i: edges[node]) {
        if(i.f==parent || centroids[i.f]) continue;
        dfs(i.f,val+i.s,times+1,node);
    }
}
int solve(int node) {
    dis1.clear();
    dis2.clear();
    //find centroid;
    get_size(node);
    int centroid = get_centroid(node);
    centroids[centroid] = true;
    dfs(centroid,0,0);
    int ans = inf;
    for(auto i: dis1) {
        int need = k-i.f;
        if(need == i.f) {
            if(dis2.find(need)!=dis2.end())
                ans = min(ans,i.s+dis2[need]);
        }else {
            if(dis1.find(need)!=dis1.end())
                ans = min(ans,i.s+dis1[need]);
        }
    }
    for(auto i: edges[centroid]) {
        if(!centroids[i.f])
            ans = min(ans,solve(i.f));
    }
    return ans;
}

int best_path(int N, int K, int H[][2], int L[]){
    n = N;
    k = K;
    edges.resize(n);
    sizes.resize(n);
    centroids.resize(n);
    pair<int,int> in[n];
    int len[n];
    for(int i = 0; i<n-1; i++) {
        in[i].f = H[i][0]; in[i].s = H[i][1]; len[i] = L[i];
        edges[in[i].f].emplace_back(in[i].s,len[i]);
        edges[in[i].s].emplace_back(in[i].f,len[i]);
    }
    auto _ = solve(0);
  	while(true){
      
    }
    if(_ == inf)
        _ =-1;
    return _;
}
/*
int main() {
    cin >> n >> k;
    edges.resize(n);
    sizes.resize(n);
    centroids.resize(n);
    pair<int,int> in[n];
    int len[n];
    for(int i = 0; i<n-1; i++) {
        cin >> in[i].f >> in[i].s >> len[i];
        edges[in[i].f].emplace_back(in[i].s,len[i]);
        edges[in[i].s].emplace_back(in[i].f,len[i]);
    }
    auto _ = solve(0);
    if(_ == inf)
        _ =-1;
    cout << _;
}*/

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