Submission #536357

#	Time	Username	Problem	Language	Result	Execution time	Memory
536357		Monarchuwu	Power Plant (JOI20_power)	C++17	100 / 100	177 ms	34808 KiB

power

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long ll;

const int N = 2e5 + 8;
int n, a[N];
char s[N];
vector<int> g[N];

void upd(int &a, int b) { if (a < b) a = b; }
int dp[N], cnt[N][3], tmp[4];
int ans;
void dfs(int u, int p) {
    for (int v : g[u]) if (v != p) {
        dfs(v, u);

        if (u == 2) {
            int bug = 1;
        }

        fill(tmp, tmp + 4, 0);
        for (int i = 0; i < 3; ++i)
            upd(tmp[i + 1], cnt[u][i] + dp[v]);

        upd(cnt[u][1], tmp[1]);
        upd(cnt[u][2], tmp[2]);
        upd(cnt[u][2], tmp[3]);
    }

    dp[u] = max({ a[u], cnt[u][1] - a[u], cnt[u][2] - a[u] });
    ans = max({ ans, cnt[u][1] + a[u], cnt[u][2] - a[u] });
}

int main() {
    cin.tie(NULL)->sync_with_stdio(false);
    cin >> n;
    for (int i = 1, u, v; i < n; ++i) {
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    cin >> (s + 1);
    for (int i = 1; i <= n; ++i) a[i] = s[i] ^ 48;

    dfs(1, 0);
    cout << ans << '\n';
}
/**  /\_/\
 *  (= ._.)
 *  / >0  \>1
**/

Compilation message (stderr)

power.cpp: In function 'void dfs(int, int)':
power.cpp:20:17: warning: unused variable 'bug' [-Wunused-variable]
   20 |             int bug = 1;
      |                 ^~~

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