SOJ 1024. Magic Island

 题目大意：给定一个n个点n-1条的连通无向图，求从任意一点出发，在不重复经过同一点的情况下，所能走过的的边的最大权值。

解题思路：深度优先搜索。

 

#include <iostream>
#include <vector>
using namespace std;

struct Edge {
    int to;
    int dis;
    Edge(int t = 0, int d = 0) {
        to = t;
        dis = d;
    }
};

const int maxn = 10005;

vector<Edge> cities[maxn];
bool visited[maxn];
int maxDis;
int dis;

void init(int n) {
    for (int i = 1; i <= n; i++) {
        visited[i] = false;
        cities[i].clear();
    }
}

void dfs(int from) {
    for (int i = 0; i < cities[from].size(); i++) {
        Edge & e = cities[from][i];
        if (!visited[e.to]) {
            visited[e.to] = true;
            dis += e.dis;
            maxDis = maxDis > dis ? maxDis : dis;
            dfs(e.to);
            visited[e.to] = false;
            dis -= e.dis;
        }
    }
}

int main() {
    int n, m;
    int from, to, dis;
    while (cin >> n >> m) {
        init(n);

        for (int i = 1; i < n; i++) {
            cin >> from >> to >> dis;
            cities[from].push_back(Edge(to, dis));
            cities[to].push_back(Edge(from, dis));
        }

        dis = 0;
        maxDis = 0;
        visited[m] = true;
        dfs(m);

        cout << maxDis << endl;
    }

    return 0;
}