제출 #135210

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
135210		fredbr	구슬과 끈 (APIO14_beads)	C++17	28 / 100	1064 ms	1272 KiB

beads

#include <bits/stdc++.h>
 
#pragma GCC optimize("O3")
 
using namespace std;
 
int const maxn = 10001;
 
struct Edge {
    int u, w, id;
};
 
struct FEdge {
    int a, b, w;
};

vector<Edge> v[maxn];
vector<FEdge> eg;

int dp[2*maxn][2];

inline int invalid(int x, int p) {
    return v[x].size() == 1 and v[x].front().u == p;
}
 
int solve(int id, int t = 0) {
    int x = eg[id].b;
    int p = eg[id].a;

    if (dp[x][t] >= 0) return dp[x][t];
    
    int d = 0;
 
    if (t == 0) {
        for (Edge const& e : v[x]) {
            if (e.u == p) continue;
 
            if (!invalid(e.u, x)) {
                d += max(solve(e.id, 1) + e.w, solve(e.id, 0));
            }
        }
    }
    else {
        int sum = solve(id, 0);
 
        for (Edge const& e : v[x]) {
            if (e.u == p) continue;
 
            if (!invalid(e.u, x))
                d = max(d, sum - max(solve(e.id, 1) + e.w, solve(e.id, 0))
                           + e.w + solve(e.id, 0));
            else
                d = max(d, sum + e.w);
        }
    }
 
    return dp[x][t] = d;
}
 
inline int test(int x) {
    memset(dp, -1, sizeof(dp));
 
    return max(solve(x), solve(x, 1) + eg[x].w);
}
 
int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
 
    int n;
    cin >> n;
 
    for (int i = 0; i < n-1; i++) {
        int a, b, w;
        cin >> a >> b >> w;
 
        v[a].push_back({b, w, i*2});
        v[b].push_back({a, w, i*2+1});

        eg.push_back({a, b, w});
        eg.push_back({b, a, w});
    }
 
    int ans = 0;
    for (int i = 0; i < 2*n - 2; i++)
        ans = max(ans, test(i));
 
    cout << ans << "\n";
}

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43