100. Same Tree

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],[1,3]

Output: true

Example 2:

Input:     1         1
          /                    2             2

        [1,2],null,2]

Output: false

Example 3:

Input:     1         1
          /        /          2   1     1   2

        [1,1],1,2]

Output: false

/**
 * 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(p == null && q == null) return true;
        if(p == null || q == null) return false;
        return p.val == q.val && isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
    }
}

意思是p.val要等于q.val，并且left和right树也要为true。Damn