题解 | #对称的二叉树#

package main


/*
 * type TreeNode struct {
 *   Val int
 *   Left *TreeNode
 *   Right *TreeNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * @param pRoot TreeNode类
 * @return bool布尔型
 */
func isSymmetrical( pRoot *TreeNode ) bool {
    if pRoot == nil {
        return true
    }
    // write code here
    var dfs func(leftNode, rightNode *TreeNode) bool
    dfs = func(leftNode, rightNode *TreeNode) bool {
        if leftNode == nil && rightNode == nil {
            return true
        }
        if (leftNode == nil && rightNode != nil) || (leftNode!=nil && rightNode == nil){
            return false
        }
        if leftNode.Val != rightNode.Val {
            return false
        }
        return dfs(leftNode.Left, rightNode.Right) && dfs(leftNode.Right, rightNode.Left)
    }
    return dfs(pRoot.Left, pRoot.Right)
}