100. Same Tree

摘要： 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 ...

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:11
/ \/ \
2323

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

Output: true

Example 2:
Input:11
/\
22

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

Output: false

Example 3:
Input:11
/ \/ \
2112

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

Output: false

難度：easy

題目：

給定兩二叉樹，寫函式檢查它們是否相同。

兩個二叉樹是否相同是由其結構和值都相同來決定。

思路：遞迴

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *int val;
 *TreeNode left;
 *TreeNode right;
 *TreeNode(int x) { val = x; }
 * }
 */
class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if (null == p && null != q || null != p && null == q) {
return false;
}

if (null == p && null == q) {
return true;
}

if (p.val != q.val) {
return false;
}

return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}
}