Submission #1286845

#	Time	Username	Problem	Language	Result	Execution time	Memory
1286845		adscoding	Power Plant (JOI20_power)	C++20	0 / 100	2 ms	576 KiB

power

#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define BIT(mask, x) ((mask >> (x)) & 1)
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

// -------------------------------------- CON CUA BO HCN --------------------------------------

const int maxn = 2e5 + 3;
int n, dp[maxn], Up[maxn], res;
vector<int> g[maxn];
bitset<maxn> has;

// --------------------------------------------------------------------------------------------

void dfs_down(int u, int p)
{
    for (int v : g[u])
    {
        if (v == p) continue;
        dfs_down(v, u);
        dp[u] += dp[v];
    }

    if (has[u])
    {
        if (dp[u] == 1) res = max(res, 2);
        --dp[u];
    }

    dp[u] = max(dp[u], (int)has[u]);
    res = max(res, dp[u]);
}

void dfs_up(int u, int p)
{
    int sum = 0;
    for (int v : g[u])
    {
        if (v == p) continue;
        sum += dp[v];
    }
    for (int v : g[u])
    {
        if (v == p) continue;
        Up[v] = Up[u] + sum - dp[v];
        res = max(res, dp[v] + Up[v]);

        if (has[v]) --Up[v];

        dfs_up(v, u);
    }
}

void solve()
{
    cin >> n;
    FOR(i, 2, n)
    {
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    } 

    FOR(i, 1, n)
    {
        char op; cin >> op;
        has[i] = op - '0';
    }

    dfs_down(1, -1);
    Up[1] = has[1];
    dfs_up(1, -1);

    cout << res;
}

signed main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    #define TASK "TEST"
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        freopen(TASK".OUT", "w", stdout);
    }
    solve();
    return 0;
}

/* NOTES:

*/

Compilation message (stderr)

power.cpp: In function 'int main()':
power.cpp:89:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen(TASK".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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