Submission #1079808

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079808		The_Blitz	Stations (IOI20_stations)	C++17	0 / 100	3 ms	1100 KiB

stations

    // TODO -> PONER ALGO AQUI
    // amigos y no mas
    // I'm in the coolest driver high
    // += O(logn) ; + = O(n)
     
    #include <bits/stdc++.h>
    #include "stations.h"
    #include <variant>
    #define fastio ios_base::sync_with_stdio(0); cin.tie(0)
    #define ones(x) __builtin_popcount(x)
    #define loga2(x) __builtin_ctzll(x)
    #define pos2(x) __builtin_clzll(x)
     
    using namespace std;
     
    typedef long long ll;
    typedef pair<int,int> ii;
    typedef pair<int,ii> iii;
    typedef pair <ii, ii> iiii;
    typedef vector <int> vi;
    typedef vector <ii> vii;
     
    const int mod = 998244353;
    const ll inf = (1LL<<62)-1;
     
    struct HASH{
      size_t operator()(const pair<int,int>&x)const{
        return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
      }
    };
     
    vector< vector<int> > G;
    vector<int> P , H;
    vector<bool> vis;
	vector<int> labels;
    int N;
     
    int st[1005][11];
     
    void dfs(int x){
      for(int i=0; i<G[x].size(); i++){
        int &y = G[x][i];
        if(!vis[y]){
          vis[y] = true;
          H[y] = H[x]+1;
          P[y] = x;
          dfs(y);
        }
      }
    }
     
    void build(){
      for(int i=0 ; i<N ; i++) st[i][0] = P[i]; 
     
      for(int i=1; i<11; i++){
        for(int j=0; j<N;j++){
          st[j][i] = st[ st[j][i-1] ][i-1];
        }
      }  
    }
     
    int query(int x, int y){
      int a = x , b= y;
      if(H[a] > H[b]){
        int dis = H[a] - H[b];
        for(int i=10; i>=0; i--){
          if(dis & (1<<i) ){
            a = st[a][i];
            dis -= (1<<i);
          }
        }
      }
     
      else if(H[a] < H[b]){
        int dis = H[b] - H[a];
        for(int i=10; i>=0; i--){
          if(dis & (1<<i) ){
            b = st[b][i];
            dis -= (1<<i);
          }
        }
      }
     
      if(a==b){
        if(a==x){
          b = y;
          int dis = (H[b] - H[a]) - 1;
          for(int i=10; i>=0; i--){
            if(dis & (1<<i) ){
              b = st[b][i];
              dis -= (1<<i);
            }
          }
          return b;
        }
        else{
          return P[x];
        }
      }
      else{
        return P[x];
      }
      // s , t , P(s)
      // s <- t (BL s-1)
      // s -> t P(s)
    }
     
    vector<int> label(int n, int k, vector<int> u, vector<int> v) {
      N = n;
      labels.clear();
      labels.resize(n);
     
      for (int i = 0; i < n; i++) {
        labels[i] = i;
      }
     
      G.clear(); H.clear();
      P.clear(); vis.clear();
     
      G.resize(n);
      H.resize(n);
      P.resize(n);
      vis.resize(n,0);
     
      for(int i=0; i<n-1;i++){
        G[u[i]].push_back(v[i]);
        G[v[i]].push_back(u[i]);
      }
     
      H[0] = 0;
      P[0] = 0;
      vis[0] = true;
      dfs(0);
      build();
     
      return labels;
    }
     
    int find_next_station(int s, int t, std::vector<int> c) {
      return query(s,t);
    }

Compilation message (stderr)

stations.cpp: In function 'void dfs(int)':
stations.cpp:41:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |       for(int i=0; i<G[x].size(); i++){
      |                    ~^~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 8
• Subtask 3: 0 / 16
• Subtask 4: 0 / 10
• Subtask 5: 0 / 61