g0201_0300.s0226_invert_binary_tree.Solution.swift Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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// #Easy #Top_100_Liked_Questions #Depth_First_Search #Breadth_First_Search #Tree #Binary_Tree
// #Data_Structure_I_Day_12_Tree #Level_2_Day_6_Tree #Udemy_Tree_Stack_Queue
// #Big_O_Time_O(n)_Space_O(n) #2024_07_01_Time_0_ms_(100.00%)_Space_15.8_MB_(77.75%)

/**
 * 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
 *     }
 * }
 */
class Solution {
    func invertTree(_ root: TreeNode?) -> TreeNode? {
            if root?.left != nil || root?.right != nil {
        let leftTree = root?.left
        let rightTree = root?.right
        
        root?.left = rightTree
        root?.right = leftTree
        
        invertTree(root?.left)
        invertTree(root?.right)
    }
    return root
    }
}