Submission #859791

#	Time	Username	Problem	Language	Result	Execution time	Memory
859791		mgl_diamond	Power Plant (JOI20_power)	C++17	100 / 100	92 ms	29584 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 ans, dp[N];

void dfs(int u, int p) {
  dp[u] = e[u];

  int sum = 0, ma = 0;
  fore(v, tree[u]) if (v != p) {
    dfs(v, u);
    sum += dp[v];
    ma = max(ma, dp[v]);
  }

  dp[u] = max(dp[u], sum - e[u]);
  ans = max(ans, max(sum - e[u], ma + 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(1, 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: 53 / 53