Submission #853542

#	Time	Username	Problem	Language	Result	Execution time	Memory
853542		thanh913	Chase (CEOI17_chase)	C++14	70 / 100	611 ms	340756 KiB

chase

#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
using ll = long long;
 
const int N = 1e5+5;
 
template<class X, class Y>
bool cmax(X &a, const Y &b) {
    return a < b ? a = b, 1 : 0;
}
 
//--------------------------------------
int n, k, a[N];
vector<int> adj[N];

ll ans, up[N][105][2], down[N][105][2];
void dfs(int u, int pr) {
    ll s = 0;
    for (auto v : adj[u]) if (v != pr) {
        dfs(v, u);
        s += a[v];
    }
 
    up[u][0][0] = 0; up[u][1][1] = s;
    for (auto v : adj[u]) if (v != pr) {
        for (int i = 0; i <= k; i++) {
            cmax(up[u][i][0], max(up[v][i][0], up[v][i][1] + a[u]));
            if (i) {
                cmax(up[u][i][1], up[v][i-1][0] + s - a[v]);
                cmax(up[u][i][1], up[v][i-1][1] + s - a[v] + a[u]);
            }
        }
    }

    down[u][0][0] = 0; down[u][1][1] = 0;
    for (auto v : adj[u]) if (v != pr) {
        for (int i = 0; i <= k; i++) {
            cmax(down[u][i][0], max(down[v][i][0], down[v][i][1]));
            if (i) {
                cmax(down[u][i][1], down[v][i-1][0] + s);
                cmax(down[u][i][1], down[v][i-1][1] + s);
            }
        }
    }
    for (int i = 0; i <= k; i++) {
        cmax(ans, max(down[u][i][0], down[u][i][1] + a[pr]));
        cmax(ans, max(up[u][i][0], up[u][i][1]));
    }
}
 
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    for (int i = 1; i < n; i++) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    for (int root = 1; root <= (n > 1e3 ? 1 : n); root++) {
        for (int i = 1; i <= n; i++) {
            memset(up[i], -63, sizeof(up[i]));
            memset(down[i], -63, sizeof(down[i]));
        }
        dfs(root, 0);
        
        for (int i = 0; i <= k; i++) {
            cmax(ans, max(up[root][i][0], up[root][i][1]));
            cmax(ans, max(down[root][i][0], down[root][i][1]));
        }
    }
    cout << ans;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 0 / 30