题目说大魔王会从$S$点走到$T$点，但事实上$S$和$T$可能不联通

这是assert代码

#include<bits/stdc++.h>
#define N 50005
using namespace std;
template<class T>void read(T&x) {
	T f=1;x=0;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while('0'<=c&&c<='9'){x=x*10+c-'0';c=getchar();}
	x*=f;
}
int n,m,S,T;
int fa[N];
int find(int x){return x==fa[x]?x:fa[x]=find(fa[x]);}
int main() {
	read(n),read(m);read(S);read(T);
	for(int i=1; i<=n; ++i)fa[i] = i;
	for(int i=1,x,y,z; i<=m; ++i) {
		read(x),read(y),read(z);
		fa[find(y)] = find(x);
	}
	assert(find(S) == find(T));
}

result