题目：原题链接（中等）
标签：图、拓扑排序、广度优先搜索、深度优先搜索
| 解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
|---|---|---|---|
| Ans 1 (Python) | O ( N + E ) O(N+E) O(N+E) | O ( N + E ) O(N+E) O(N+E) | 180ms (53.74%) |
| Ans 2 (Python) | |||
| Ans 3 (Python) |
解法一：
class Solution:
def eventualSafeNodes(self, graph1: List[List[int]]) -> List[int]:
size = len(graph1)
ans = []
count = collections.Counter()
queue = collections.deque()
graph2 = [[] for _ in range(size)] # 入度图
for i in range(size):
count[i] = len(graph1[i])
for j in graph1[i]:
graph2[j].append(i)
if count[i] == 0:
queue.append(i)
ans.append(i)
while queue:
i1 = queue.popleft()
for i2 in graph2[i1]:
count[i2] -= 1
if count[i2] == 0:
queue.append(i2)
ans.append(i2)
ans.sort()
return ans
