leetcod-261-Graph Valid Tree

zem_nezer

于 2019-02-12 13:17:36 发布

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本文链接：https://blog.youkuaiyun.com/zem_nezer/article/details/87083176

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本文探讨了如何使用深度优先搜索（DFS）算法来检测图中是否存在环，并对比了广度优先搜索（BFS）。作者详细解释了DFS的实现过程，包括迭代所有节点并检查当前节点和下一个节点是否相同等关键步骤。

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Error:
cannot solve it. So stupid.

Use dfs to solve it. Actually we can use BFS, which is simpler. But I think dfs is something we use mostly. In dfs, iterate all node, then count current node and next node is the same, the tricky part is the return value.

My solution is:

is_cycle(edges, visited, current, previous):
	if(current == previous)
		return true;
	if(visited[current] == true)
		return true;
	res = false
	for(e : edges[current]):
		if(e == previous)
			continue;
		res |= is_cycle(edges, visited, e, current);
	return res;