Submission #759075

#	Time	Username	Problem	Language	Result	Execution time	Memory
759075		kirakosyan	The Xana coup (BOI21_xanadu)	C++17	0 / 100	55 ms	31964 KiB

xanadu

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <cmath>
#include <map>
#include <string>
#include <ios>
#include <iomanip>
#include <deque>
#include <queue>
#include <list> 
#include <stack>

#define FASTIO ios_base::sync_with_stdio(0); cin.tie(NULL);
using ll = long long;
using namespace std;
vector<vector<ll>>gp;
vector<ll>v;
vector<vector<vector<ll>>>dp;
void dfs(ll u,ll p){
    ll cnt=1e18,lox=1e18,ans=0,ans1=0;
    for(ll& x:gp[u]){
        if(x!=p){
        dfs(x,u);
        dp[u][0][0]+=min(dp[x][0][0],dp[x][1][0]);
        dp[u][1][0]+=min(dp[x][1][1],dp[x][0][1]);
        if(min(dp[x][0][0],dp[x][1][0])==dp[x][1][0]) ans++;  
        if(min(dp[x][0][1],dp[x][1][1])==dp[x][1][1]) ans1++;  
        cnt=min(cnt,abs(dp[x][0][0]-dp[x][1][0]));
            lox=min(lox,abs(dp[x][1][1]-dp[x][0][1]));
        }
        
    }
    if(gp[u].size()==1&&u!=0){
            if(v[u]==0){
            dp[u][0][0]=0;
            dp[u][0][1]=1e17;
            dp[u][1][0]=1e17;
            dp[u][1][1]=1;
            }
            else{
            dp[u][0][0]=1e17;
            dp[u][0][1]=0;
            dp[u][1][0]=1;
            dp[u][1][1]=1e17;
            }
    }
    else{
        
        dp[u][0][1]=dp[u][0][0]+1;
        dp[u][1][1]=dp[u][1][0]+1;
        
        if((v[u]==1&&ans%2==0)||(v[u]==0&&ans%2==1)){
            dp[u][0][0]+=cnt;
        }
        if((v[u]==1&&ans%2==1)||(v[u]==0&&ans%2==0)){
            dp[u][0][1]+=cnt;
        }
        if((v[u]==1&&ans1%2==0)||(v[u]==0&&ans1%2==1)){
            dp[u][1][1]+=lox;
        }
        if((v[u]==1&&ans1%2==1)||(v[u]==0&&ans1%2==0)){
            dp[u][1][0]+=lox;
        }
    }
  
}
void solve(){
     ll n; cin >> n;
    v=vector<ll>(n);
    gp=vector<vector<ll>>(n);
    dp=vector<vector<vector<ll>>>(n,vector<vector<ll>>(2,vector<ll>(2)));
    for(ll i=0;i<n-1;i++){
        ll u,v; cin >> u >> v;
        --u,--v;
        gp[u].push_back(v);
        gp[v].push_back(u);
    }
    for(ll i=0;i<n;i++){
        cin >> v[i];
    }
    
    dfs(0,-1);
    //   cout<<dp[4][0][1]<<endl;
    // cout<<dp[4][1][1]<<endl;
    //     cout<<dp[4][0][0]<<endl;
    //     cout<<dp[4][1][0]<<endl;













        
    // cout<<dp[0][0][1]<<endl;
    // cout<<dp[0][1][1]<<endl;
    //     cout<<dp[0][0][0]<<endl;
    //     cout<<dp[0][1][0]<<endl;

    if(min({dp[0][0][0],dp[0][1][0]})>=n){
        cout<<"impossible"<<endl;
    }
   else  cout<<min({dp[0][0][0],dp[0][1][0]});
}
signed main() {
        FASTIO
        ll t=1;
       // cin >> t;
        while (t--) {
            solve();
        }
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 40
• Subtask 5: 0 / 30