Submission #763037

#	Time	Username	Problem	Language	Result	Execution time	Memory
763037		vjudge1	Power Plant (JOI20_power)	C++17	0 / 100	2 ms	4948 KiB

power

#include<bits/stdc++.h>
using namespace std;

#define taskname "template"
#define ll long long
#define ld double
#define fi first
#define se second
#define vi vector<int>
#define pii pair<int,int> 
#define vii vector<pii>
#define vvi vector<vi>
#define pb push_back
#define eb emplace_back

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

const int MN=2e5+5;

int n;
int a,b;
string s;
vi son[MN];
int color[MN];//on or off
bool check[MN];
int ans;

void bfs(int u){
    int best=0;
    queue<int> q;
    q.push(u);

    while(!q.empty()){
        u=q.front(); q.pop();
        if(check[u]) continue;
        check[u]=true; int cnt=color[u];

        for(int v:son[u]){
            if(check[v]) continue;
            cnt+=color[v]; q.push(v);
        }
        best=max(best,cnt-(color[u]<<1));
    }
    ans+=max(0,best-1);
    // cout<<max(0,best-1)<<'\n';
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    /*
    freopen(taskname".inp","r",stdin);
    freopen(taskname".out","w",stdout);
    */

    cin>>n;
    for(int i=1;i<n;++i){
        cin>>a>>b;
        son[a].eb(b); son[b].eb(a);
    }
    cin>>s;
    for(int i=0;i<n;++i){
        color[i+1]=s[i]-'0';
    }
    int root=-1,max1=0;
    for(int i=1;i<=n;++i){
        int cnt=color[i];
        for(int v:son[i]){
            cnt+=color[v];
        }
        // cout<<"Case "<<i<<": "<<cnt<<'\n';
        if(cnt>max1){
            max1=cnt; root=i;
        }
    }
    ans=max1-(color[root]<<1);
    // cout<<ans<<'\n';
    
    check[root]=true;
    for(int v:son[root]){
        // cout<<"Case "<<v<<": ";
        if(color[v]) bfs(v);
    }
    cout<<ans;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53