第4个点会MLE我知道，但是为啥会WA两个点啊qwq

#include <bits/stdc++.h>

using namespace std;

const int N = 100, M = 10000;

int n, m, K, A, B;
int rh[N], h[N], e[M], w[M], ne[M], idx;

void add(int h[], int a, int b, int c)
{
    w[idx] = c, e[idx] = b, ne[idx] = h[a], h[a] = idx ++ ;
}

#define x first
#define y second

typedef pair<int, int> PII;
bool st[N];
int dist[N];

void dij()
{
    priority_queue<PII, vector<PII>, greater<PII>> pq;
    memset(dist, 0x3f, sizeof dist);
    
    pq.push({0, B});
    dist[B] = 0;
    
    while (pq.size())
    {
        auto t = pq.top();
        pq.pop();
        
        int u = t.y, udist = t.x;
        if (st[u]) continue;
        st[u] = 1;
        dist[u] = udist;
        
        for (int i = rh[u]; ~i; i = ne[i])
        {
            int v = e[i];
            if (dist[v] > dist[u] + w[i])
            {
                dist[v] = dist[u] + w[i];
                pq.push({dist[v], v});
            }
        }
    }
}

typedef pair<int, PII> PIII;
typedef pair<PIII, string> PIS;
string res;
char str[100];

int astar()
{
    // A can't reach B
    if (dist[A] == 0x3f3f3f3f) return -1;

    priority_queue<PIS, vector<PIS>, greater<PIS>> pq;
    int cnt = 0;

    sprintf(str, "%d", A);
    string t = str;
    pq.push({{dist[A], {0, A}}, t});
    st[A] = 1;
    while (pq.size())
    {
        auto t = pq.top();
        pq.pop();

        int u = t.x.y.y, udist = t.x.y.x;
        if (u == B) cnt ++ ;
        if (cnt == K) 
        {
            res = t.y;
            return udist;
        }

        unordered_set<int> st;
        int len = t.y.size(), p = 0, x = 0;
        while (p < len)
        {
            if (t.y[p] == '-')
            {
                st.insert(x);
                x = 0;
                p ++ ;
            }
            x = x * 10 + t.y[p] - '0';
            p ++ ;
        }
        // 不要忘记最后一个点
        st.insert(x);

        for (int i = h[u]; ~i; i = ne[i])
        {
            int v = e[i], vdist = udist + w[i];
            if (st.count(v)) continue;
            sprintf(str, "-%d", v);
            PIS ne = {{dist[v] + vdist, {vdist, v}}, t.y + string(str)};
            pq.push(ne);
        }
    }

    return -1;
}

void print(int ans)
{
    // printf("%d\n", ans);
    cout << res << endl;
}

int main()
{
    memset(h, -1, sizeof h);
    memset(rh, -1, sizeof rh);

    // input
    scanf("%d%d%d%d%d", &n, &m, &K, &A, &B);
    for (int i = 0; i < m; i ++ )
    {
        int a, b, c;
        scanf("%d%d%d", &a, &b, &c);
        add(h, a, b, c);
        add(rh, b, a, c);
    }
    
    dij(); // get the distance to B
    
    int ans = astar();

    if (ans == -1) puts("No");
    else print(ans);
    
    return 0;
}