100.Same Tree

 

 

 

 

 

 

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def isSameTree(self, p: TreeNode, q: TreeNode) -> bool:
        if p == None or q == None:
            if p == None and q == None:
                return True
            else:
                return False
        elif p.val == q.val:
            ans_l = self.isSameTree(p.left, q.left)
            ans_r = self.isSameTree(p.right, q.right)
            if ans_l == True and ans_r == True:
                return True
            else:
                return False
        else:
            return False

 

Java 版：

一起遍历两颗树

　　1. 当都为 null ,则返回 true ;

　　2. 其中一个为 null ,另一个不为 null，返回 false ;

　　3. 都不为null, 但节点的值不相等，也返回 false；

　　4. 否则，继续遍历左右子树。

class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p == null && q == null) return true;
        if(p == null || q == null) return false;
        if(p.val != q.val) return false;
        boolean leftRes = isSameTree(p.left, q.left);
        boolean rightRes = isSameTree(p.right, q.right);
        return leftRes && rightRes;    
    }
}