public void dfs(int v) {
if (hasCycle) {
return;
}
if (color[v] != 2) {
color[v] = 1;
if (graph[v] == null) {
color[v] = 2;
answer.add(v);
return;
}
for (int i = 0; i < graph[v].size(); i++) {
int to = graph[v].get(i);
if (color[to] == 0) {
dfs(to);
}
if (color[to] == 1) {
hasCycle = true;
return;
}
}
color[v] = 2;
answer.add(v);
}
}
public void topSort() {
for (int i = 1; i < graph.length; i++) {
if (color[i] == 0) {
dfs(i);
}
}
Collections.reverse(answer);
}
