Language: C++

#include<iostream>
#define LL long long
#define dob complex<double>
#define Abs(a) ((a) < 0 ? (-(a)) : (a))
#define Max(a, b) ((a) > (b) ? (a) : (b))
#define Min(a, b) ((a) < (b) ? (a) : (b))
#define Swap(a, b) ((a) ^= (b), (b) ^= (a), (a) ^= (b))
#define writeln(x) (write(x), putchar('\n'))
#define lowbit(x) ((x)&(-(x)))
using namespace std;
const int N = 100000;
const int yzd = 1e9+7;
void read(int &x) {
    char ch; bool flag = 0;
    for (ch = getchar(); !isdigit(ch) && ((flag |= (ch == '-')) || 1); ch = getchar());
    for (x = 0; isdigit(ch); x = (x<<1)+(x<<3)+ch-48, ch = getchar());
    x *= 1-2*flag;
}
void print(int x) {if (x > 9) print(x/10); putchar(x%10+48); }
void write(int x) {if (x < 0) putchar('-'); print(Abs(x)); }
 
int n, m, s, t, u, v, c;
struct tt {int to, next, cost; }edge[(N<<2)+5];
int path[N+5], top;
int ans1[N+5], ans2[N+5], vis[N+5], in[N+5];
LL dist1[N+5], dist2[N+5];
queue<int>Q;
vector<int>to[N+5];
 
void add(int u, int v, int c) {
    edge[++top].to = v, edge[top].cost = c, edge[top].next = path[u], path[u] = top;
}
void SPFA(int s, LL *dist) {
    dist[s] = 0; Q.push(s); vis[s] = 1;
    while (!Q.empty()) {
    int u = Q.front(); Q.pop(); vis[u] = 0;
    for (int i = path[u]; i; i = edge[i].next)
        if (dist[edge[i].to] > dist[u]+edge[i].cost) {
        dist[edge[i].to] = dist[u]+edge[i].cost;
        if (!vis[edge[i].to]) {
            vis[edge[i].to] = 1; Q.push(edge[i].to);
        }
        }
    }
}
void topsort(int s, LL *dist, int *ans) {
    for (int u = 1; u <= n; u++) {
    to[u].clear();
    for (int i = path[u]; i; i = edge[i].next)
        if (dist[edge[i].to] == dist[u]+edge[i].cost) to[u].push_back(edge[i].to), ++in[edge[i].to];
    }
    ans[s] = 1; Q.push(s);
    while (!Q.empty()) {
    int u = Q.front(), size = to[u].size(); Q.pop();
    for (int i = 0; i < size; i++) {
        if (--in[to[u][i]] == 0) Q.push(to[u][i]); (ans[to[u][i]] += ans[u]) %= yzd;
    }
    }
}
void work() {
    read(n), read(m), read(s), read(t);
    for (int i = 1; i <= m; i++) {
    read(u), read(v), read(c); add(u, v, c); add(v, u, c);
    }
    memset(dist1, 127/3, sizeof(dist1));
    SPFA(s, dist1); topsort(s, dist1, ans1);
    memset(dist2, 127/3, sizeof(dist2));
    SPFA(t, dist2); topsort(t, dist2, ans2);
    int ans = 1ll*ans1[t]*ans1[t]%yzd;
    for (int u = 1; u <= n; u++) {
    if (dist1[u] == dist2[u] && dist2[u]*2 == dist1[t]) (ans -= 1ll*ans1[u]*ans1[u]%yzd*ans2[u]%yzd*ans2[u]%yzd) %= yzd;
    for (int i = path[u]; i; i = edge[i].next)
        if (dist1[u]+edge[i].cost+dist2[edge[i].to] == dist1[t] && dist1[u]*2 < dist1[t] && dist2[edge[i].to]*2 < dist1[t])
        (ans -= 1ll*ans1[u]*ans1[u]%yzd*ans2[edge[i].to]%yzd*ans2[edge[i].to]%yzd) %= yzd;
    }
    writeln((ans+yzd)%yzd);
}
int main() {
int johnny=9;
    work();
    return 0;
}


Compiler output:
a.cc:27:1: error: 'queue' does not name a type
   27 | queue<int>Q;
      | ^~~~~
a.cc:28:1: error: 'vector' does not name a type
   28 | vector<int>to[N+5];
      | ^~~~~~
a.cc: In function 'void SPFA(int, long long int*)':
a.cc:34:18: error: 'Q' was not declared in this scope
   34 |     dist[s] = 0; Q.push(s); vis[s] = 1;
      |                  ^
a.cc: In function 'void topsort(int, long long int*, int*)':
a.cc:48:5: error: 'to' was not declared in this scope; did you mean 'tt'?
   48 |     to[u].clear();
      |     ^~
      |     tt
a.cc:52:17: error: 'Q' was not declared in this scope
   52 |     ans[s] = 1; Q.push(s);
      |                 ^
a.cc:55:23: error: invalid operands of types 'int' and '<unresolved overloaded function type>' to binary 'operator<'
   55 |     for (int i = 0; i < size; i++) {
      |                     ~~^~~~~~
a.cc:56:18: error: 'to' was not declared in this scope; did you mean 'tt'?
   56 |         if (--in[to[u][i]] == 0) Q.push(to[u][i]); (ans[to[u][i]] += ans[u]) %= yzd;
      |                  ^~
      |                  tt
a.cc:56:57: error: 'to' was not declared in this scope; did you mean 'tt'?
   56 |         if (--in[to[u][i]] == 0) Q.push(to[u][i]); (ans[to[u][i]] += ans[u]) %= yzd;
      |                                                         ^~
      |                                                         tt
a.cc: In function 'void work()':
a.cc:65:5: error: 'memset' was not declared in this scope
   65 |     memset(dist1, 127/3, sizeof(dist1));
      |     ^~~~~~
a.cc:2:1: note: 'memset' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    1 | #include<iostream>
  +++ |+#include <cstring>
    2 | #define LL long long