【yLOI2018】锦鲤抄

#include<stack>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define N 500500
#define M 2000500
#define mod 1000000007
#define ri register int

using namespace std;

inline int read() {
  int ret=0; char ch=getchar();
  while (ch<‘0‘ || ch>‘9‘) ch=getchar();
  while (ch>=‘0‘ && ch<=‘9‘) ret*=10,ret+=(ch-‘0‘),ch=getchar();
  return ret;
}

stack<int> s; vector<int> to[N];
int dfn[N],low[N],a[N],bel[N],id[N];
int n,m,k,u[M],v[M],sc=0,vc=0,ins[N],siz[N];

void tarjan(int x) {
  dfn[x]=low[x]=++sc; s.push(x); ins[x]=1;
  for (ri i=0;i<to[x].size();i++) {
    int y=to[x][i];
    if (!dfn[y]) {
      tarjan(y);
      low[x]=min(low[x],low[y]);
    }
    else {
      if (ins[y]) low[x]=min(low[x],dfn[y]);
    }
  }
  if (low[x]==dfn[x]) {
    ++vc;
    while (1) {
      int t=s.top(); s.pop(); ins[t]=0;
      bel[t]=vc;
      siz[vc]++;
      if (t==x) break;
    }
  }
}

bool cmp(int x,int y) {
  return a[x]>a[y];
}

int main() {
  n=read(); m=read(); k=read();
  for (ri i=1;i<=n;i++) a[i]=read();
  for (ri i=1;i<=m;i++) {
    u[i]=read(); v[i]=read();
    to[u[i]].push_back(v[i]);
  }
  for (ri i=1;i<=n;i++) if (!dfn[i]) tarjan(i);
  for (ri i=1;i<=m;i++) {
    if (bel[u[i]]!=bel[v[i]]) siz[bel[v[i]]]++;
  }
  for (ri i=1;i<=n;i++) id[i]=i;
  sort(id+1,id+n+1,cmp);
  int ans=0,cnt=0;
  for (ri i=1;i<=n;i++) {
    int cur=id[i];
    if (siz[bel[cur]]>1) {
      siz[bel[cur]]--;
      ans+=a[cur];
      if (++cnt==k) {
        printf("%d\n",ans);
        return 0;
      }
    }
  }
  printf("%d\n",ans);
  return 0;
}