Submission #596764

#	Time	Username	Problem	Language	Result	Execution time	Memory
596764		1bin	Chase (CEOI17_chase)	C++14	100 / 100	306 ms	180948 KiB

chase

#include <bits/stdc++.h>
 
using namespace std;
 
#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 1e5 + 5;
ll n, k, a[NMAX], x, y, u[NMAX][105], d[NMAX][105], ans;
vector<int> adj[NMAX];
 
void dfs(int x, int bef){
    ll sum = 0;
    for(int nx : adj[x]) sum += a[nx];
    
    u[x][1] = sum;
    for(int nx : adj[x]){
        if(nx == bef) continue;
        dfs(nx, x);
        for(int i = 1; i <= k; i++){
            ans = max(ans, u[x][i] + d[nx][k - i]);
            u[x][i] = max({u[x][i], u[x][i - 1], u[nx][i], u[nx][i - 1] + sum - a[nx]});
            d[x][i] = max({d[x][i], d[x][i - 1], d[nx][i], d[nx][i - 1] + sum - a[bef]});
        }
    }
    
    reverse(all(adj[x]));
    memset(u[x], 0, sizeof(u[x]));
    memset(d[x], 0, sizeof(d[x]));
    u[x][1] = sum;
    for(int nx : adj[x]){
        if(nx == bef) continue;
        for(int i = 1; i <= k; i++){
            ans = max(ans, u[x][i] + d[nx][k - i]);
            u[x][i] = max({u[x][i], u[x][i - 1], u[nx][i], u[nx][i - 1] + sum - a[nx]});
            d[x][i] = max({d[x][i], d[x][i - 1], d[nx][i], d[nx][i - 1] + sum - a[bef]});
        }
    }
    return;
}
 
int main(void){
    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 = 0; i < n - 1; i++){
        cin >> x >> y;
        adj[x].emplace_back(y);
        adj[y].emplace_back(x);
    }
    dfs(1, 0);
    cout << ans;
    return 0;
}

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