subtask Re 求调

#include<bits/stdc++.h>
#pragma GCC Optimize(3,"fast")
#define int long long
#define MAXN 121000
#define maxn 22001000
#define INF 0x3f3f3f3f3f3f3f3f
using namespace std;
int n,m,s,t,head[MAXN],h[MAXN],vis[MAXN],gap[MAXN],flow[MAXN],cnt=1;
struct cmp
{
	inline bool operator ()(int x,int y)const
	{
		return h[x]<h[y];
	}
};
priority_queue<int,vector<int>,cmp> pq;
queue<int> q;
struct edge
{
	int to,nxt,val;
}e[maxn<<1];
inline void add(int x,int y,int z)
{
	e[++cnt].to=y;
	e[cnt].nxt=head[x];
	head[x]=cnt;
	e[cnt].val=z;
}
inline int read()
{
	int x=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))
	{
		if(ch=='-')
		{
			f=-1;
		}
		ch=getchar();
	}
	while(isdigit(ch))
	{
		x=(x<<3)+(x<<1)+(ch^'0');
		ch=getchar();
	}
	return x*f;
}
inline bool bfs()
{
	memset(h,INF,sizeof(h));
	h[t]=0;
	q.push(t);
	while(q.size())
	{
		int x=q.front();
		q.pop();
		for(int i=head[x];i;i=e[i].nxt)
		{
			int y=e[i].to;
			if(e[i^1].val&&h[y]>h[x]+1)
			{
				h[y]=h[x]+1;
				q.push(y);
			}
		}
	}
	return h[s]!=INF;
}
inline void push(int x)
{
	for(int i=head[x];i;i=e[i].nxt)
	{
		int y=e[i].to;
		if(e[i].val&&h[y]+1==h[x])
		{
			int f=min(e[i].val,flow[x]);
			e[i].val-=f;
			e[i^1].val+=f;
			flow[x]-=f;
			flow[y]+=f;
			if(y!=s&&y!=t&&!vis[y])
			{
				pq.push(y);
				vis[y]=1;
			}
			if(!flow[x])
			{
				break;
			}
		}
	}
}
inline void relabel(int x)
{
	h[x]=INF;
	for(int i=head[x];i;i=e[i].nxt)
	{
		int y=e[i].to;
		if(e[i].val&&(h[y]+1<h[x]))
		{
			h[x]=h[y]+1;
		}
	}
}
inline int hlpp()
{
	if(!bfs())
	{
		return 0;
	}
	h[s]=n;
	for(int i=1;i<=n;i++)
	{
		if(h[i]!=INF)
		{
			gap[h[i]]++;
		}
	}
	for(int i=head[s];i;i=e[i].nxt)
	{
		int y=e[i].to;
		if(int f=e[i].val)
		{
			e[i].val-=f;
			e[i^1].val+=f;
			flow[y]+=f;
			if(y!=s&&y!=t&&!vis[y])
			{
				pq.push(y);
				vis[y]=1;
			}
		}
	}
	while(pq.size())
	{
		int x=pq.top();
		pq.pop();
		vis[x]=0;
		push(x);
		if(flow[x])
		{
			gap[h[x]]--;
			if(!gap[h[x]])
			{
				for(int i=1;i<=n;i++)
				{
					if(i!=s&&i!=t&&h[i]>h[x]&&h[i]<n+1)
					{
						h[i]=n+1;
					}
				}
			}
			relabel(x);
			gap[h[x]]++;
			pq.push(x);
			vis[x]=1;
		}
	}
	return flow[t];
}
signed main()
{
	n=read(),m=read(),s=read(),t=read();
	for(int i=1;i<=m;i++)
	{
		int x=read(),y=read(),z=read();
		add(x,y,z);
		add(y,x,0);
	}
	printf("%lld",hlpp());
	return 0;
}