Submission #321237

#	Time	Username	Problem	Language	Result	Execution time	Memory
321237		tushar_2658	Power Plant (JOI20_power)	C++14	100 / 100	233 ms	29856 KiB

power

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

const int maxn = 200005;

vector<int> edges[maxn];
int a[maxn], dp[maxn], ans = 0;

void dfs(int x, int p){
  int cur = a[x], res = 0;
  dp[x] = cur;
  for(auto i : edges[x]){
    if(i != p){
      dfs(i, x);
      res += dp[i];
    }
  }
  res -= cur;
  dp[x] = max(dp[x], res);
  ans = max(ans, dp[x]);
}

void dfs1(int x, int p, int carry){
  int res = carry - a[x];
  for(auto i : edges[x]){
    if(i != p){
      res += dp[i];
    }
  }
  ans = max(ans, res);
  for(auto i : edges[x]){
    if(i != p){
      dfs1(i, x, max(a[x], res - dp[i]));
    }
  }
}

int main(int argc, char const *argv[])
{
  ios::sync_with_stdio(false);
  cin.tie(0);

  int n;
  cin >> n;
  for(int i = 0; i < n - 1; ++i){
    int x, y;
    cin >> x >> y;
    edges[x].push_back(y);
    edges[y].push_back(x);
  }
  string s;
  cin >> s;
  int cnt = 0;
  for(int i = 1; i <= n; ++i){
    a[i] = (s[i - 1] - '0');
    cnt += a[i];
  }
  ans = min(2, cnt);
  dfs(1, 1);
  dfs1(1, 1, 0);
  cout << ans << endl;

  return 0;
}

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