Submission #939749

#	Time	Username	Problem	Language	Result	Execution time	Memory
939749		iskhakkutbilim	Chase (CEOI17_chase)	C++17	0 / 100	266 ms	176480 KiB

chase

#include <bits/stdc++.h>
 
using namespace std;
 
#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long
 
using i64 = long long;
 
template <class F, class _S>
bool chmin(F &u, const _S &v){
    bool flag = false;
    if ( u > v ){
        u = v; flag |= true;
    }
    return flag;
}
 
template <class F, class _S>
bool chmax(F &u, const _S &v){
    bool flag = false;
    if ( u < v ){
        u = v; flag |= true;
    }
    return flag;
}
 
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int n, k; cin >> n >> k;
    vector <int> a(n);
    for ( auto &u: a ) cin >> u;
    vector <vector<int>> G(n);
    for ( int i = 0; i + 1 < n; i++ ){
        int u, v; cin >> u >> v;
        --u, --v;
        G[u].pb(v), G[v].pb(u);
    }
    if ( !k ){ return cout << "0\n", 0; }
    const int inf = 1e15;
    auto opt = [&](int rt){
        vector <vector<ar<int,2>>> dp(n, vector <ar<int,2>> (k + 1, {-inf, -inf}));
        vector <int> s(n);
        for ( int i = 0; i < n; i++ ){
            for ( auto &v: G[i] ){
                s[i] += a[v];
            }
        }	
        auto dfs = [&](auto dfs, int u, int p) -> void{
            for ( auto &v: G[u] ){
                if ( v == p ) continue;
                for ( int j = 0; j <= k; j++ ){
                    for ( auto t: {0, 1} ){
                        if ( j - t < 0 ) continue;
                        for ( auto f: {0, 1} ){
                            chmax(dp[v][j][t], dp[u][j - t][f] + (s[v] - a[u]) * t - !f * a[v]);
                        }
                    }
                }
                dfs(dfs, v, u);
            }
        };
        dp[rt][1][1] = s[rt];
        dfs(dfs, rt, -1);
        int ret = 0;
        for ( int i = 0; i < n; i++ ){
            for ( int j = 0; j <= k; j++ ){
                for ( auto f: {0, 1} ){
                    chmax(ret, dp[i][j][f]);
                }
            }
        }
        return ret;
    };
    int ans = 0;
    for ( int i = 0; i < n; i++ ){
        chmax(ans, opt(i));
        if ( n > 1e3 ) break;
    }
    cout << ans;
 
    cout << '\n';
}
 
/*
12 2
2 3 3 8 1 5 6 7 8 3 5 4
2 1
2 7
3 4
4 7
7 6
5 6
6 8
6 9
7 10
10 11
10 12
*/

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