100-Same Tree

100-Same Tree | Links:

题意

Given two binary trees, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:
Input:     1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:
Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:
Input:     1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

思路

• 树：双pre，同时走两边
• 递归调用

分析:

• Time: O(n)
• Space: O(n)