Same Tree

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.

/**
 * 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)
            return true;
        if(p!= null && q != null){
            if(p.val == q.val){
                boolean x = isSameTree(p.left,q.left);
                boolean y = isSameTree(p.right,q.right);
                return x==true && y==true;
            }
        }
        return false;
    }
}

第一次把判断条件写错了 

return x==true && y==true;

写成了

return x == y;