kosaraju求助，始终20分

#include<iostream>
#include<vector>
#define mn 1010
#define FOR(i,x,y) for(int i=x;i<=y;++i)
#define ROF(i,x,y) for(int i=x;i>=y;--i)
using namespace std;
int n,m;
int a[mn],c[mn];
int mark[mn];
int f[mn];
int U[mn],V[mn];
int S[mn],top;
int ans;
bool vis[mn];
vector<int>G[mn],G2[mn];
inline void dfs1(int u)
{
	vis[u]=1;
	for(int v:G[u])if(!vis[v])dfs1(v);
	S[++top]=u;
}
inline void dfs2(int u)
{
	mark[u]=top,c[top]+=a[u];
	for(int v:G2[u])if(!mark[v])dfs2(v);
}
inline void dp(int u)
{
	if(f[u])return;
	for(int v:G[u])
	{
		if(!f[v])dp(v);
		f[u]=max(f[u],f[v]);
	}
	f[u]+=c[u];
}
int main()
{
	cin>>n>>m;
	FOR(i,1,n)cin>>a[i];
	FOR(i,1,m)
	{
		cin>>U[i]>>V[i];
		G[U[i]].push_back(V[i]);
		G2[V[i]].push_back(U[i]);
	}
	FOR(i,1,n)if(!vis[i])dfs1(i);
	top=0;
	ROF(i,n,1)
	{
		if(!mark[S[i]])top++,dfs2(S[i]);
		G[i].clear();
	}
	FOR(i,1,m)if(mark[U[i]]!=mark[V[i]])G[mark[U[i]]].push_back(mark[V[i]]);
	FOR(i,1,top)
	{
		if (!f[i])dp(i);
		ans=max(ans,f[i]);
	}
	cout<<ans;
	return 0;
}