#include <bits/stdc++.h>
using namespace std;
const int N = 1e4 + 10;
int n, m;
vector <int> e[N], ne[N];
int dfn[N], low[N], tot;
int stk[N], instk[N], top;
int scc[N], cnt;
int w[N], nw[N], dp[N];

void tarjan(int x)
{
    dfn[x] = low[x] = ++tot;
    stk[++top] = x, instk[x] = 1;
    for(int y : e[x])
    {
        if(!dfn[y])
        {
            tarjan(y);
            low[x] = min(low[x], low[y]);
        }
        else if(instk[x])
            low[x] = min(low[x], dfn[y]);
    }
    if(dfn[x] == low[x])
    {
        int y; ++ cnt;
        do
        {
            y = stk[top--];
            instk[y] = 0;
            scc[y] = cnt;
        } while (y != x);
        
    }
}
int main()
{
    int a, b, ans = 0;
    cin >> n >> m;
    for(int i = 1; i <= n; i++) cin >> w[i];
    for(int i = 1; i <= m; i++)
    {
        cin >> a >> b;
        e[a].push_back(b);
    }
    for(int i = 1; i <= n; i++)
        if(!dfn[i]) tarjan(i);
    for(int x = 1; x <= n; x++)
    {
        nw[scc[x]] += w[x];
        for(int y : e[x])
        {
            a = scc[x], b = scc[y];
            if(a != b) ne[a].push_back(b);
        }
    }
    for(int x = cnt; x; x --)
    {
        if(dp[x] == 0)
            dp[x] = nw[x];
        for(int y : ne[x])
            dp[y] = max(dp[y], dp[x]+nw[y]);
    }
    for(int i = 1; i <= cnt; i++)
        ans = max(ans, dp[i]);
    cout << ans << endl;
    return 0;
}

错误的测试点 ： WA #2

in : 10 20 970 369 910 889 470 106 658 659 916 964 3 2 3 6 3 4 9 5 8 3 5 8 9 1 9 7 9 8 7 5 3 7 7 8 1 7 10 2 1 10 4 8 2 6 3 1 3 5 8 5

out(ans): 6911 mine : 5995