|
| 1 | +/** |
| 2 | + * Definition for a binary tree node. |
| 3 | + * public class TreeNode { |
| 4 | + * public var val: Int |
| 5 | + * public var left: TreeNode? |
| 6 | + * public var right: TreeNode? |
| 7 | + * public init() { self.val = 0; self.left = nil; self.right = nil; } |
| 8 | + * public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; } |
| 9 | + * public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) { |
| 10 | + * self.val = val |
| 11 | + * self.left = left |
| 12 | + * self.right = right |
| 13 | + * } |
| 14 | + * } |
| 15 | + */ |
| 16 | +classSolution{ |
| 17 | +func getMaxHeight(of root:TreeNode?)->Int{ |
| 18 | +guardlet root= rootelse{return0} |
| 19 | +return1+ max( |
| 20 | +getMaxHeight(of: root.left), |
| 21 | +getMaxHeight(of: root.right) |
| 22 | +) |
| 23 | +} |
| 24 | + |
| 25 | +func isBalanced(_ root:TreeNode?)->Bool{ |
| 26 | +guardlet root= rootelse{returntrue} |
| 27 | + |
| 28 | +letleftHeight=getMaxHeight(of: root.left) |
| 29 | +letrightHeight=getMaxHeight(of: root.right) |
| 30 | +letdifference=abs(leftHeight- rightHeight) |
| 31 | + |
| 32 | + // early exits |
| 33 | +guard difference<=1else{returnfalse} |
| 34 | +guardisBalanced(root.left)==trueelse{returnfalse} |
| 35 | +guardisBalanced(root.right)==trueelse{returnfalse} |
| 36 | + |
| 37 | +returntrue |
| 38 | +} |
| 39 | +} |