Submission #656199

#	Time	Username	Problem	Language	Result	Execution time	Memory
656199		Ronin13	Power Plant (JOI20_power)	C++14	100 / 100	270 ms	27564 KiB

power

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;

const int NMAX = 2e5 + 1;

int dp[NMAX][3];
char c[NMAX];
vector <vector <int> > g(NMAX);
int ans = 0;

void dfs(int v, int e = -1){
    for(int to : g[v]){
        if(to == e) continue;
        dfs(to, v);
    }
    int x = c[v] - '0';
    int sum = -x;
    int mx = 0;
    for(int to : g[v]){
        if(to == e) continue;
        sum += max(dp[to][1], dp[to][0]);
        mx = max(mx, dp[to][1]);
    }
    if(x) dp[v][1] = max(sum, 1), ans = max({ans, sum, 1, mx});
    else dp[v][1] = sum, ans = max(ans, sum);
    if(x){
        int mx = 0;
        int mx1 = 0;
        int sum = 0;
        for(int to : g[v]){
            mx = max(mx, dp[to][2]);
            mx1 = max(mx1, dp[to][1]);
        }
        dp[v][2] = max(mx1 + 1, mx - 1);
        ans = max(ans, mx);
        ans = max(ans, mx1 + 1);
    }
    else{
        int mx = 0;
        for(int to : g[v]){
            mx = max(mx, dp[to][2]);
        }
        dp[v][2] = mx;
        ans = max(ans, mx);
    }
}

int main(){
    int n; cin >> n;
    for(int i = 1; i < n; i++){
        int a, b; cin >> a >> b;
        g[a].pb(b);
        g[b].pb(a);
    }
    for(int i = 1; i <= n; i++)
        cin >> c[i];
    dfs(1);
    cout << ans;
    return 0;
}

Compilation message (stderr)

power.cpp: In function 'void dfs(int, int)':
power.cpp:37:13: warning: unused variable 'sum' [-Wunused-variable]
   37 |         int sum = 0;
      |             ^~~

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