제출 #1126296

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1126296		AIF_is_carving	경주 (Race) (IOI11_race)	C++20	0 / 100	5 ms	7488 KiB

race

#include<bits/stdc++.h> 
using namespace std;
 
typedef long long LL;
 
const int N = 200010;
vector<pair<int, int>> graph[N];
vector<bool> is_removed(N, 0);
vector<int> subtree_size(N, 0);
vector<int> pathsize(N, 0);
vector<int> depth(N, 0);
int ans = 1e9;
int k;

int get_subtree_size(int node, int parent = -1) {
    subtree_size[node] = 1;
    for (auto child : graph[node]) {
        if (child.first == parent || is_removed[child.first]) { continue; }
        subtree_size[node] += get_subtree_size(child.first, node);
    }
    return subtree_size[node];
}

int get_centroid(int node, int tree_size, int parent = -1) {
    for (auto child : graph[node]) {
        if (child.first == parent || is_removed[child.first]) { continue; }
        if (subtree_size[child.first] * 2 > tree_size) {
            return get_centroid(child.first, tree_size, node);
        }
    }
    return node;
}


void dfs(int v, int parent, map<int, int> &m){
    for(auto u: graph[v]){
        if(u.first!= parent && !is_removed[u.first]){
            pathsize[u.first] = pathsize[v] + u.second;
            depth[u.first] = depth[v] +1;
            if(m.find(pathsize[u.first]) == m.end()) m[pathsize[u.first]] = depth[u.first];
            else m[pathsize[u.first]] = min(depth[u.first], m[pathsize[u.first]]);
        }
    }
}

/** Build up the centroid decomposition recursively */
void build_centroid_decomp(int node = 0) {
    int centroid = get_centroid(node, get_subtree_size(node));

    // do something
    pathsize[centroid] = 0;
    map<int, vector<pair<int, int>> > pathlist;
    //cout<<centroid<<" : \n";
    for(auto child : graph[centroid]){
        map<int, int> m;
        dfs(child.first, -1, m);
        for(auto p: m){
            //cout<<p.first<<" "<<p.second<<"\n";
            pathlist[p.first].push_back({p.second,child.first});
        }
    }

    auto it = pathlist.begin();
    for(; it != pathlist.end(); it++){
        sort((*it).second.begin(), (*it).second.end());
    }

    for(auto p: pathlist){
        int vertice = (p.second)[0].second;
        int length = (p.second)[0].first;
        if(pathlist.find(k - length) != pathlist.end()){
            int nextvertice = pathlist[k - length][0].second;
            int nextlength = pathlist[k - length][0].first;

            if(vertice == nextvertice){
                if(pathlist[k-length].size() == 1) continue;
                nextvertice = pathlist[k - length][1].second;
                nextlength = pathlist[k - length][1].first;
            }

            ans = min(ans, length + nextlength);
        }
    }

    if(pathlist.find(k) != pathlist.end()){
        ans = min(ans, pathlist[k][0].first);
    }

    is_removed[centroid] = true;

    for (auto child : graph[centroid]) {
        if (is_removed[child.first]) { continue; }
        build_centroid_decomp(child.first);
    }
}

// void solve(){
//     int n; cin>>n>>k;
//     for(int i = 1; i<n; i++){
//         int u,v,w ;
//         cin>>u>>v>>w;
//         graph[u].push_back({v, w});
//         graph[v].push_back({u, w});
//     }
    

//     build_centroid_decomp(0);
 
 
//     //cout<<ans<<"\n";
//     printf("%lld\n", ans);
// }

int best_path(int N, int K, int h[][2], int L[]){
    ans = 1e9;

    int n = N;
    k = K;
    for(int i = 0; i<n-1; i++){
        graph[h[i][0]].push_back({h[i][1], L[i]});
        graph[h[i][1]].push_back({h[i][0], L[i]});
    }

    build_centroid_decomp(0);
    if(ans > 1e8) ans = -1;
    return ans;
}

// signed main(){
//     // ios_base::sync_with_stdio(false);
//     // cin.tie(NULL);
//     // cout.tie(NULL);
 
//     int t=1; //cin>>t;
 
//     while(t--){
//         solve();
//     }
 
// }

• Subtask 1: 0 / 9
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