Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

答案

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