题解 | #二叉树的镜像#

/*class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */
/**
 * 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 TreeNode类
 */
export function Mirror(pRoot: TreeNode): TreeNode {
    // write code here
    if(!pRoot) return pRoot

    let temp = Mirror(pRoot.left)
    pRoot.left = Mirror(pRoot.right)
    pRoot.right = temp    

    return pRoot
}