题解 | #对称的二叉树#

前序遍历

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    boolean preOrder(TreeNode rRoot,TreeNode lRoot){
        if(rRoot == null && lRoot == null){
            return true;
        }else if(rRoot == null && lRoot != null){
            return false;
        }else if(rRoot != null && lRoot == null){
            return false;
        }
        if(rRoot.val != lRoot.val){
            return false;
        }
        boolean left = preOrder(rRoot.left,lRoot.right);
        boolean right = preOrder(rRoot.right,lRoot.left);
        return left&&right;
    }
    boolean isSymmetrical(TreeNode pRoot) {
         return preOrder(pRoot,pRoot);
    }
}