Submission #1149007

#	Time	Username	Problem	Language	Result	Execution time	Memory
1149007		KhoaDuy	Mousetrap (CEOI17_mousetrap)	C++20	0 / 100	557 ms	70748 KiB

mousetrap

#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
const int MAXN=1e6;
int DP[MAXN+1];
vector<vector<int>> graph(MAXN+1);
vector<int> path;
bool in[MAXN+1]={false};
bool getpath(int u,int p,int t){
    path.push_back(u);
    if(u==t){
        return true;
    }
    for(int v:graph[u]){
        if(v!=p){
            if(getpath(v,u,t)){
                return true;
            }
        }
    }
    path.pop_back();
    return false;
}
void DFS(int u,int p){
    DP[u]=0;
    vector<int> child;
    for(int v:graph[u]){
        if(v!=p&&!in[v]){
            DFS(v,u);
            child.push_back(DP[v]+1);
        }
    }
    sort(child.begin(),child.end(),greater<int>());
    for(int i=0;i<child.size();i+=2){
        child[i]=1;
    }
    for(int i=0;i<child.size();i++){
        DP[u]+=child[i];
    }
}
signed main(){
    //freopen("mousetrap.inp","r",stdin);
    //freopen("mousetrap.out","w",stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n,t,root;
    cin >> n >> t >> root;
    for(int i=0;i<n-1;i++){
        int u,v;
        cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    getpath(root,-1,t);
    int ans=0;
    for(int i=0;i<path.size();i++){
        in[path[i]]=true;
    }
    for(int i=0;i+1<path.size();i++){
        DFS(path[i],-1);
        ans+=DP[path[i]];
    }
    cout << ans;
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35