这段代码能通过所有讨论区和题解提到的 hack 数据。

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

template<typename T>inline char _read(T &x) {char t=getchar();bool tmp=0;x=0;while(t<'0'||t>'9'){if(t=='-')tmp=1;t=getchar();};while('0'<=t&&t<='9'){x=(x<<1)+(x<<3)+(t^48);t=getchar();}if(tmp)x=-x;return t;}
void read(){}template<typename T,typename ...T2>inline void read(T &x,T2 &...oth) {_read(x);read(oth...);}
template<typename T>inline void read(T *l,T *r) {T *cur=l;while(cur!=r){_read(*cur);++cur;}}
inline void write(){putchar('\n');}
template<typename T>inline void _write(T x) {if(x<0){putchar('-');x=-x;}if(x/10)_write(x/10);putchar((x%10)^48);}
template<typename T,typename ...T2>inline void write(T x,T2 ...oth) {_write(x);putchar(' ');write(oth...);}

#define int long long

const int mod=998244353;
const int N=2e3+3;
const int M=3e5+5;
const int inf=1e18;

int s[4],n;
int head[M],nxt[M*2],to[M*2],v[M*2],tot=-1;
int d[N][4];

struct node {
	int x,v;
	bool operator()(const node &x,const node &y) {
		return x.v>y.v;
	}
};
priority_queue<node,vector<node>,node> q;

inline void dij(const int t) {
	q.push({s[t],0});
	while(!q.empty()) {
		node cur=q.top();
		q.pop();
		if(~d[cur.x][t]) continue;
		d[cur.x][t]=cur.v;
		for(int i=head[cur.x];~i;i=nxt[i]) {
			if(~d[to[i]][t]) continue;
			q.push({to[i],cur.v+v[i]});
		}		
	}
}
inline void add(int x,int y,int w) {
	nxt[++tot]=head[x];
	head[x]=tot;
	to[tot]=y;
	v[tot]=w;
}
inline bool chk(int x) {
	return d[x][0]+d[x][1]==d[s[1]][0]&&d[x][2]+d[x][3]==d[s[3]][2];
}
inline int getlen(int x,int y) {
	int ans=d[x][0]-d[y][0];
	if(ans*ans!=(d[x][1]-d[y][1])*(d[x][1]-d[y][1])) return -1;
	if(ans*ans!=(d[x][2]-d[y][2])*(d[x][2]-d[y][2])) return -1;
	if(ans*ans!=(d[x][3]-d[y][3])*(d[x][3]-d[y][3])) return -1;
	return abs(ans);
}

signed main() {
#if defined(fre)
	fropen();
#endif
	memset(head,-1,sizeof head);
	memset(nxt,-1,sizeof nxt);
	memset(d,-1,sizeof d);
	int m;read(n,m);
	read(s,s+4);
	while(m--) {
		int u,v,x;read(u,v,x);
		add(u,v,x);
		add(v,u,x);
	}
	dij(0);
	dij(1);
	dij(2);
	dij(3);
	int ans=0;
	for(int i=1;i<=n;i++)
		if(chk(i))
		for(int j=1;j<=n;j++)
			if(chk(j))
			ans=max(ans,getlen(i,j));
	write(ans);
#if defined(fre)
	frclose();
#endif
	return 0;
}//写题偶遇神秘数据，拼尽全力无法战胜。