notebook/code/TopologicalSort.cpp

//
struct edge { int v, next; };
bool TopSortDFS(int v, edge e[], int g[], int u[], int &m) {
  u[v] = -2;
  for(int i = g[v]; i != -1; i=e[i].next)
    if(u[e[i].v]==-2)
      return false;
    else if(u[e[i].v]==-1 && !TopSortDFS(e[i].v, e, g, u, m))
      return false;
    u[v] = --m;
    return true;
}
bool TopSort(edge e[], int g[], int n, int list[]) {
  static int u[maxn];
  int m = n;
  memset(u, 255, sizeof(u));
  for(int i = 0; i < n; i++)
    if(u[i] == -1 && !TopSortDFS(i,e,g,u,m))
      return false;
  for(int i = 0; i < n; i++)
    list[u[i]] = i;
  return true;
}