拓扑排序 hihoCoder1175 拓扑排序·二

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按照拓扑排序的顺序去扩展病毒数量，这样相当于所有节点只走了一遍就出了结果

#include<cstdio>#include<cstring>#include<cstdlib>#include<cmath>#include<vector>#include<queue>#include<algorithm>using namespace std;typedef long long LL;const int mod=142857;const int MX=100000+5;const int INF=0x3f3f3f3f;int vis[MX],A[MX],S[MX];vector<int>G[MX];int main(){    int n,m,k;    while(~scanf("%d%d%d",&n,&m,&k)){        memset(A,0,sizeof(A));        memset(vis,0,sizeof(vis));        for(int i=1;i<=n;i++) G[i].clear();        for(int i=1;i<=k;i++){            int x;            scanf("%d",&x);            S[x]++;        }        for(int i=1;i<=m;i++){            int u,v;            scanf("%d%d",&u,&v);            G[u].push_back(v);            A[v]++;        }        int ans=0;        queue<int>work;        for(int i=1;i<=n;i++){            if(A[i]==0) work.push(i);        }        while(!work.empty()){            int fp=work.front();            work.pop();            ans=(ans+S[fp])%mod;            for(int i=0;i<G[fp].size();i++){                int v=G[fp][i];                S[v]=(S[v]+S[fp])%mod;                A[v]--;                if(!A[v]) work.push(v);            }        }        printf("%d\n",ans);    }    return 0;}

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