Submission #859768

#	Time	Username	Problem	Language	Result	Execution time	Memory
859768		mgl_diamond	Power Plant (JOI20_power)	C++17	47 / 100	1525 ms	16020 KiB

power

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;

#define foru(i, l, r) for(int i=(l); i<=(r); ++i)
#define ford(i, l, r) for(int i=(l); i>=(r); --i)
#define fore(x, v) for(auto &x : v)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)x.size()

void setIO() {
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  if (fopen("input.inp", "r")) {
    freopen("input.inp", "r", stdin);
    freopen("input.out", "w", stdout);
  }
}

const int N = 2e5+5;
int n, m, e[N];
string s;
vector<int> tree[N];

int dp[N];

void dfs(int u, int p, int root) {
  // only root
  dp[u] = e[u];
//  if (u == 5) {
//    cout << e[u] << "\n";
//  }

  int sum = 0;
  fore(v, tree[u]) if (v != p) {
    dfs(v, u, root);

    // only one child
    if (u == root) dp[u] = max(dp[u], dp[v] + 1);

    // take more than two child
    sum += dp[v];
  }

//  if (u == 5) cout << dp[5] << "\n";
//  if (u == 5) cout << sum - e[u] << "\n";
  dp[u] = max(dp[u], sum - e[u]);
}

int main() {
  setIO();

  cin >> n;
  foru(i, 2, n) {
    int u, v;
    cin >> u >> v;
    tree[u].push_back(v);
    tree[v].push_back(u);
  }
  cin >> s;
  foru(i, 1, n) e[i] = (s[i-1] == '1');

//  dfs(4, 4, 4);
//  cout << dp[4] << " " << dp[3] << "\n";
//  cout << dp[1] << " " << dp[2] << "\n";
//  cout << dp[5] << "\n";
  int ans = 0;
  foru(i, 1, n) if (e[i]) {
    dfs(i, i, i);
    ans = max(ans, dp[i]);
//    if (dp[i] == 4) {
//      cout << "ddm\n";
//      cout << i;
//      return 0;
//    }
  }
  cout << ans;
}

Compilation message (stderr)

power.cpp: In function 'void setIO()':
power.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen("input.inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:17:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     freopen("input.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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