思路：广度优先搜索。队列记录路径节点，奇数点+1，偶数点+2，走到goal时结束搜索。

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

typedef struct node
{
    int num;
    int sum;
    node() {}
    node(int num, int sum)
    {
        this->num = num;
        this->sum = sum;
    }
} node;

int main()
{
    int n, m, s, goal, limit;
    while (scanf("%d %d %d %d %d", &n, &m, &s, &goal, &limit) != EOF)
    {
        // n个点  m条路  起点s  终点t  时限limit
        vector<vector<int>> g(n + 1, vector<int>(n + 1, 1e5));
        for (int i = 0; i < m; i++)
        {
            int a, b, c;
            scanf("%d %d %d", &a, &b, &c);
            if (g[a][b] > c)
                g[a][b] = g[b][a] = c;
        }
        int res = 0;
        int state = 0;
        queue<node> queue;
        vector<bool> vis(n + 1, false);
        queue.push(node(s, 0));
        while (!queue.empty())
        {
            node t = queue.f...