Not the best

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

#define inf 1061109567
#define inf_m 63
#define mx 5005
struct node
{
    int u, cost;
    node(){;}
    node(int _u, int _cost)
    {
        u = _u;
        cost = _cost;
    }
};
bool operator < (node A, node B)
{
    return B.cost < A.cost;
}
vector<node>adj[mx];
int dis_f[mx], dis_s[mx];

void dijkstra(int s, int e)
{
    memset(dis_f, 63, sizeof(dis_f));
    memset(dis_s, 63, sizeof(dis_s));
    priority_queue<node>pq;
    dis_f[s] = 0;
    pq.push(node(s, 0));
    node top, temp;
    while(!pq.empty())
    {
        top = pq.top();
        pq.pop();
        if(top.cost > dis_s[top.u])
            continue;
        for(auto it : adj[top.u])
        {
            temp = it;
            if(dis_f[it.u] > top.cost + it.cost)
            {
                dis_s[it.u] = dis_f[it.u];
                dis_f[it.u] = top.cost + it.cost;
                pq.push(node(it.u, dis_f[it.u]));
            }
            else if(top.cost + it.cost > dis_f[it.u] && top.cost + it.cost < dis_s[it.u])
            {
                dis_s[it.u] = top.cost + it.cost;
                pq.push(node(it.u, dis_s[it.u]));
            }
        }
    }
}

int main()
{
    int n, r, t, i, j, u, v, c;
    scanf("%d", &t);
    for(i = 1; i <= t; i++)
    {
        scanf("%d %d", &n, &r);
        while(r--)
        {
            scanf("%d %d %d", &u, &v, &c);
            adj[u].push_back(node(v, c));
            adj[v].push_back(node(u, c));
        }
        dijkstra(1, n);
        printf("Case %d: %d\n", i, dis_s[n]);
        while(n)
            adj[n--].clear();
    }
    return 0;
}