一本通1518：抢掠计划

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <stack>
#include <queue>
#include <climits>
using namespace std;
typedef long long ll;
const int N = 2e6 + 45;
int n, m;
struct edge {
    int from;
    int to;
    int next;
} e[N];
int cnt, head[N];
stack<int> q;
void add(int u, int v) {
    cnt++;
    e[cnt].from = u;
    e[cnt].to = v;
    e[cnt].next = head[u];
    head[u] = cnt;
}
int val[N], A[N], a[N], b[N];
int root, num;
int sccnt, t;
int dfn[N], low[N], siz[N], color[N];
bool vis[N];
int mapp[N];
void tarjan(int u) {
    t++;
    dfn[u] = low[u] = t;
    q.push(u);
    vis[u] = true;

    for (int i = head[u]; i ; i = e[i].next) {
        int v = e[i].to;

        if (dfn[v] == 0) {
            tarjan(v);
            low[u] = min(low[u], low[v]);
        } else if (vis[v])
            low[u] = min(low[u], dfn[v]);
    }

    if (low[u] == dfn[u]) {
        int w;
        sccnt++;

        do {
            w = q.top();
            q.pop();
            vis[w] = false;
            siz[sccnt] ++;
            color[w] = sccnt;
            val[sccnt] += A[w];
        } while (u != w);
    }
}

void SPFA(int u) {
    queue<int> op;
    op.push(u);
    vis[u] = true;
    mapp[u] += val[u];

    while (!op.empty()) {
        int x = op.front();
        op.pop();
        vis[x] = false;

        for (int i = head[x] ; i ; i = e[i].next) {
            int y = e[i].to;

            if (mapp[y] > mapp[x] + val[y]) {
                mapp[y] = mapp[x] + val[y];

                if (vis[y] == false) {
                    op.push(y);
                    vis[y] = true;
                }
            }
        }
    }
}
int main() {
    scanf("%d%d", &n, &m);

    for (int i = 1; i <= m; i++) {
        scanf("%d%d", &a[i], &b[i]);
        add(a[i], b[i]);
    }

    for (int i = 1; i <= n; i++) {
        scanf("%d", &A[i]);
        A[i] *= -1;
    }

    scanf("%d%d", &root, &num);

    for (int i = 1; i <= n; i++) {
        if (dfn[i] == 0)
            tarjan(i);
    }

    for (int i = 1; i <= cnt; i++) {
        e[i].from = 0;
        e[i].to = 0;
        e[i].next = 0;
        head[i] = 0;
    }

    cnt = 0;
    fill(vis, vis + N, 0);

    for (int i = 1; i <= m; i ++) {
        int x = color[a[i]];
        int y = color[b[i]];

        if (x != y)
            add(x, y);
    }

    SPFA(color[root]);
    int ans = 0;

    for (int i = 1;  i <= num; i ++) {
        int x;
        scanf("%d", &x);
        ans = min(ans, mapp[color[x]]);
    }

    printf("%d", -ans);
    return 0;
}