Submission #331881

#	Time	Username	Problem	Language	Result	Execution time	Memory
331881		phathnv	Power Plant (JOI20_power)	C++11	100 / 100	214 ms	30508 KiB

power

#include <bits/stdc++.h>

#define mp make_pair
#define X first
#define Y second

using namespace std;

typedef long long ll;
typedef pair <int, int> ii;

const int N = 2e5 + 1;

int n;
vector <int> adj[N];
string s;
int a[N], dp[N][2];

void readInput(){
    cin >> n;
    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    cin >> s;
}

void dfs(int u, int p){
    dp[u][0] = -a[u];
    dp[u][1] = a[u];
    int maxVal = 0;
    for(int v : adj[u]){
        if (v == p)
            continue;
        dfs(v, u);
        dp[u][0] += max(a[v], dp[v][0]);
        maxVal = max(maxVal, dp[v][0]);
        maxVal = max(maxVal, a[v]);
    }
    dp[u][1] += maxVal;
    dp[u][0] = max(dp[u][0], dp[u][1] - 2 * a[u]);
}

void solve(){
    for(int i = 1; i <= n; i++)
        a[i] = s[i - 1] - '0';
    dfs(1, -1);
    int res = 0;
    for(int i = 1; i <= n; i++){
        //cerr << i << ' ' << dp[i][0] << ' ' << dp[i][1] << endl;
        res = max(res, dp[i][0]);
        res = max(res, dp[i][1]);
    }
    cout << res;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    readInput();
    solve();
    return 0;
}

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