Submission #389120

#	Time	Username	Problem	Language	Result	Execution time	Memory
389120		phathnv	Beads and wires (APIO14_beads)	C++11	0 / 100	4 ms	4940 KiB

beads

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const int N = 2e5 + 7;
const int INF = 1e9 + 7;

struct Edge{
    int v, c;
    Edge(int _v, int _c){
        v = _v;
        c = _c;
    }
};

int n, dp[N][4];
vector<Edge> adj[N];

void Dfs(int u, int p){
    dp[u][0] = 0;
    dp[u][1] = -INF;
    dp[u][2] = -INF;
    dp[u][3] = -INF;
    for(Edge e : adj[u]){
        int v = e.v;
        int c = e.c;
        if (v == p)
            continue;
        Dfs(v, u);
        int nxtDp[4] = {-INF, -INF, -INF, -INF};

        nxtDp[0] = max(nxtDp[0], dp[u][0] + dp[v][0]);
        nxtDp[0] = max(nxtDp[0], dp[u][0] + dp[v][1] + c);
        nxtDp[0] = max(nxtDp[0], dp[u][0] + dp[v][3]);

        nxtDp[1] = max(nxtDp[1], dp[u][0] + dp[v][0] + c);
        nxtDp[1] = max(nxtDp[1], dp[u][1] + dp[v][0]);
        nxtDp[1] = max(nxtDp[1], dp[u][1] + dp[v][1] + c);
        nxtDp[1] = max(nxtDp[1], dp[u][1] + dp[v][3]);

        nxtDp[2] = max(nxtDp[2], dp[u][0] + dp[v][3] + c);
        nxtDp[2] = max(nxtDp[2], dp[u][2] + dp[v][0]);
        nxtDp[2] = max(nxtDp[2], dp[u][2] + dp[v][1] + c);
        nxtDp[2] = max(nxtDp[2], dp[u][2] + dp[v][3]);

        nxtDp[3] = max(nxtDp[3], dp[u][1] + dp[v][0] + c);
        nxtDp[3] = max(nxtDp[3], dp[u][1] + dp[v][3] + c);
        nxtDp[3] = max(nxtDp[3], dp[u][2] + dp[v][0] + c);
        nxtDp[3] = max(nxtDp[3], dp[u][3] + dp[v][1] + c);
        nxtDp[3] = max(nxtDp[3], dp[u][3] + dp[v][3]);

        dp[u][0] = nxtDp[0];
        dp[u][1] = nxtDp[1];
        dp[u][2] = nxtDp[2];
        dp[u][3] = nxtDp[3];

        //cerr << u << ' ' << v << ' ' << dp[u][0] << ' ' << dp[u][1] << ' ' << dp[u][2] << ' ' << dp[u][3] << endl;
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;
    for(int i = 1; i < n; i++){
        int u, v, c;
        cin >> u >> v >> c;
        adj[u].push_back(Edge(v, c));
        adj[v].push_back(Edge(u, c));
    }

    Dfs(1, -1);
    cout << max(dp[1][0], dp[1][3]);

    return 0;
}

/*
10
5 6 9
2 3 5
1 10 8
4 5 9
2 7 8
5 7 10
6 9 4
2 8 9
1 7 5

10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/

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