0226-invert-binary-tree.swift

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * public var val: Int
 * public var left: TreeNode?
 * public var right: TreeNode?
 * public init() { self.val = 0; self.left = nil; self.right = nil; }
 * public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
 * public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
 * self.val = val
 * self.left = left
 * self.right = right
 * }
 * }
 */
classSolution{
func invertTree(_ root:TreeNode?)->TreeNode?{
guard root !=nilelse{return root }
letleft=invertTree(root?.left)
letright=invertTree(root?.right)
 root?.left = right
 root?.right = left
return root
}

}