算法笔记_面试_0.刷leetcode_基础知识范围

冷不防 2023-02-23 12:29 131阅读 0赞

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时间复杂度：不考虑系数！

与n的关系

例子

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图示:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NoeWpoeXAxMQ_size_16_color_FFFFFF_t_70 2][]

主定理：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NoeWpoeXAxMQ_size_16_color_FFFFFF_t_70 3][]

**面试题举例：**

*  **二叉树的前中后序遍历的时间复杂度为多少？**
    
     *  答：都是O(n), 可以根据主定理算出。或者说： 不管那种遍历方式结节都只访问一次，所以线性于节点数，所以时间复杂度是O(n）
     *  同理：图的遍历/DFS(深度优先)/BFS(广度优先)，时间复杂度也都是O(n)
     *  二分查找：时间复杂度：O(logn)
 *  **空间复杂度**： 数组的长度为n,则时间复杂度为O(n)； 对于递归，递归的最大深度即为其时间复杂度。

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