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| #include <iostream>
#include <cstdio>
#include <stack>
#include <queue>
using namespace std;
const int N = 5e5 + 10, M = 5e5 + 10;
namespace SCC
{
int n, m, w[N];
bool vis[N];
int idx, hd[N], nxt[M], edg[M];
int cnt, stmp, id[N], dfn[N], low[N];
stack<int> stk;
void tarjan(int x)
{
dfn[x] = low[x] = ++stmp;
stk.push(x);
vis[x] = true;
for (int i = hd[x]; ~i; i = nxt[i])
if (!dfn[edg[i]])
{
tarjan(edg[i]);
low[x] = min(low[x], low[edg[i]]);
}
else if (vis[edg[i]])
low[x] = min(low[x], dfn[edg[i]]);
if (dfn[x] == low[x])
{
int y;
cnt++;
do
{
y = stk.top();
stk.pop();
vis[y] = false;
id[y] = cnt;
} while (x != y);
}
}
void add(int a, int b)
{
nxt[++idx] = hd[a];
hd[a] = idx;
edg[idx] = b;
}
}
namespace SP
{
bool vis[N];
int n, m;
int w[N], d[N], st, p, ed[N];
int idx, hd[N], nxt[M], edg[M];
void add(int a, int b)
{
nxt[++idx] = hd[a];
hd[a] = idx;
edg[idx] = b;
}
int spfa()
{
d[st] = w[st];
queue<int> q;
q.push(st);
vis[st] = true;
while (!q.empty())
{
int t = q.front();
q.pop();
vis[t] = false;
for (int i = hd[t]; ~i; i = nxt[i])
if (d[t] + w[edg[i]] > d[edg[i]])
{
d[edg[i]] = d[t] + w[edg[i]];
if (!vis[edg[i]])
{
q.push(edg[i]);
vis[edg[i]] = true;
}
}
}
int res = 0;
for (int i = 1; i <= p; i++)
res = max(res, d[ed[i]]);
return res;
}
}
int main()
{
using namespace SCC;
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; i++)
SP::hd[i] = hd[i] = -1;
for (int i = 1, a, b; i <= m; i++)
{
scanf("%d%d", &a, &b);
add(a, b);
}
for (int i = 1; i <= n; i++)
if (!dfn[i])
tarjan(i);
for (int i = 1; i <= n; i++)
scanf("%d", &w[i]);
scanf("%d%d", &SP::st, &SP::p);
SP::st = id[SP::st];
for (int i = 1, a; i <= SP::p; i++)
{
scanf("%d", &a);
SP::ed[i] = id[a];
}
for (int i = 1; i <= n; i++)
{
SP::w[id[i]] += w[i];
for (int j = hd[i]; ~j; j = nxt[j])
if (id[i] != id[edg[j]])
SP::add(id[i], id[edg[j]]);
}
printf("%d", SP::spfa());
return 0;
}
|