Submission #1256811

#	Time	Username	Problem	Language	Result	Execution time	Memory
1256811		son2008	Power Plant (JOI20_power)	C++20	100 / 100	78 ms	31300 KiB

power

#include <bits/stdc++.h>
using namespace std;
#define ii pair<int, int>
#define fi first
#define se second
// #define int long long
#define ll long long
#define ld double
#define mp make_pair
#define lg2 30
#define iii pair<int, ii>
#define iiii pair<ii, ii>
#define base 29
#define eps 1e-8
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
int dx[] = {0LL, 0LL, 1, -1, 1, 1, -1, -1};
int dy[] = {1, -1, 0LL, 0LL, 1, -1, 1, -1};
const int maxn = 4e5 + 5;
const int mod = 1e9 + 7;
int n, dp[maxn], ans, s[maxn];
vector<int> a[maxn];
void dfs(int u, int cha)
{
    if (a[u].size() == 1 && u != 1)
    {
        ans = max(ans, s[u]);
        dp[u] = s[u];
    }
    for (int v : a[u])
    {
        if (v == cha)
            continue;
        dfs(v, u);
        ans = max(ans, dp[v] + s[u]);
        dp[u] += dp[v];
    }
    dp[u] -= s[u];
    dp[u] = max(dp[u], s[u]);
    ans = max(ans, dp[u]);
}
signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
#define task "task"
    if (fopen(task ".inp", "r"))
    {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    cin >> n;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        a[u].push_back(v);
        a[v].push_back(u);
    }
    for (int i = 1; i <= n; i++)
    {
        char c;
        cin >> c;
        s[i] = (c == '1');
    }
    dfs(1, -1);
    cerr << dp[3] << '\n';
    cout << ans;
    cerr << endl
         << "TIME : " << clock() * 0.001 << "s" << endl;
}

Compilation message (stderr)

power.cpp: In function 'int main()':
power.cpp:50:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:51:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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