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[LeetCode]Remove Duplicate Letters

题目描述:

Given a string which contains only lowercase letters, remove duplicate letters so that every letter appear once and only once. You must make sure your result is the smallest in lexicographical order among all possible results.

Example:

Given "bcabc" ...

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[LeetCode]Minimum Depth of Binary Tree

题目描述:

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

题目大意:

给定一棵二叉树,计算其最小深度。

最小深度是指从根节点出发到达最近的叶子节点所需要经过的节点个数。

解题思路:

DFS或者BFS均可,详见代码。

Python代码(DFS ...

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