Submission #620032

#	Time	Username	Problem	Language	Result	Execution time	Memory
620032		AbdelmagedNour	Mergers (JOI19_mergers)	C++17	0 / 100	61 ms	21940 KiB

mergers

#include<bits/stdc++.h>
using namespace std;
const int N=500005;
int p[N][20],val[N],dep[N],st[N],id=-1;
vector<vector<int>>adj;
void pre_dfs(int v,int par){
    p[v][0]=par;
    st[v]=++id;
    for(int i=1;i<20;i++)p[v][i]=p[p[v][i-1]][i-1];
    for(auto&u:adj[v]){
        if(u==par)continue;
        dep[u]=dep[v]+1;
        pre_dfs(u,v);
    }
}
void dfs_up(int v,int par){
    for(auto&u:adj[v]){
        if(u==par)continue;
        dfs_up(u,v);
    }
    val[par]+=val[v];
}
int LCA(int u,int v){
    if(u==v)return u;
    if(dep[u]<dep[v])swap(u,v);
    int k=dep[u]-dep[v];
    for(int i=__lg(k+1);i>=0;i--){
        if(k&(1<<i))u=p[u][i];
    }
    if(u==v)return u;
    for(int i=__lg(dep[u]);i>=0;i--){
        if(p[u][i]==p[v][i])continue;
        u=p[u][i];
        v=p[v][i];
    }
    return p[u][0];
}
int cnt(int v,int par){
    int res=0;
    for(auto&u:adj[v]){
        if(u==par)continue;
        res+=cnt(u,v);
    }
    return max(res,(val[v]==0&&v!=1?1:0));
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n,k;
    cin>>n>>k;
    adj.resize(n+1);
    for(int i=1;i<n;i++){
        int u,v;
        cin>>u>>v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    pre_dfs(1,0);
    vector<vector<int>>state(k+1);
    for(int i=1;i<=n;i++){
        int x;
        cin>>x;
        state[x].push_back(i);
    }
    for(int i=1;i<=k;i++){
        sort(state[i].begin(),state[i].end(),[](int i,int j){
                return st[i]<st[j];
             });
        for(int j=1;j<state[i].size();j++){
            int u=state[i][j-1],v=state[i][j];
            val[u]++;val[v]++;
            val[LCA(u,v)]-=2;
        }
    }
    dfs_up(1,0);
    cout<<(cnt(1,0)+1)/2;
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:71:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |         for(int j=1;j<state[i].size();j++){
      |                     ~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30