[Swift]LeetCode563. 二叉樹的坡度 | Binary Tree Tilt

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Given a binary tree, return the tilt of the whole tree.

The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has tilt 0.

The tilt of the whole tree is defined as the sum of all nodes' tilt.

Example:

Input: 
         1
       /   \
      2     3
Output: 1
Explanation: 
Tilt of node 2 : 0
Tilt of node 3 : 0
Tilt of node 1 : |2-3| = 1
Tilt of binary tree : 0 + 0 + 1 = 1

 Note:

1. The sum of node values in any subtree won't exceed the range of 32-bit integer.
2. All the tilt values won't exceed the range of 32-bit integer.

---

給定一個二叉樹，計算整個樹的坡度。

一個樹的節點的坡度定義即爲，該節點左子樹的結點之和和右子樹結點之和的差的絕對值。空結點的的坡度是0。

整個樹的坡度就是其全部節點的坡度之和。

示例:

輸入: 
         1
       /   \
      2     3
輸出: 1
解釋: 
結點的坡度 2 : 0
結點的坡度 3 : 0
結點的坡度 1 : |2-3| = 1
樹的坡度 : 0 + 0 + 1 = 1

注意:

1. 任何子樹的結點的和不會超過32位整數的範圍。
2. 坡度的值不會超過32位整數的範圍。

---

44ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     func findTilt(_ root: TreeNode?) -> Int {
16         var sum = 0
17         
18         func getAllTilts(_ root: TreeNode?) -> Int {
19             guard let root = root else { return 0 }
20             var lVal = 0
21             var rVal = 0
22             if root.left != nil {
23                 lVal = getAllTilts(root.left)
24             }
25             if root.right != nil {
26                 rVal = getAllTilts(root.right)
27             }
28             sum += abs(lVal - rVal)
29             return lVal + rVal + root.val
30         }
31         
32         getAllTilts(root)
33         return sum
34     }
35 }

---

48ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     var tilt = 0
16     
17     func findTilt(_ root: TreeNode?) -> Int {
18         aux(root)
19         return tilt
20     }
21     func aux(_ root:TreeNode?) -> Int {
22         if root == nil {
23             return 0 
24         }
25         let tiltLeft = aux(root?.left)
26         let tiltRight = aux(root?.right)
27         
28         tilt += abs(tiltLeft - tiltRight) 
29         
30         return tiltLeft + tiltRight + root!.val
31     }
32 }

---

68ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     var tilt = 0
16     
17     func findTilt(_ root: TreeNode?) -> Int {
18         traverse(root)
19         return tilt
20     }
21     
22     func traverse(_ root: TreeNode?) -> Int {
23         guard let root = root else { return 0 }
24         
25         let l = traverse(root.left)
26         let r = traverse(root.right)
27         
28         tilt += abs(l - r)
29         
30         return l + r + root.val
31     }
32 }

---

88ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     var tilt = 0
16     func findTilt(_ root: TreeNode?) -> Int {
17                 
18         helper(root)       
19         return  tilt
20     }
21     
22     func helper(_ root: TreeNode?) -> Int {
23         guard let root = root else {
24             return 0
25         }
26         
27         let left = helper(root.left)
28         let right = helper(root.right)
29         tilt +=  abs(left - right)
30         
31         return root.val + left + right
32     }
33 }

---

92ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     
16     var sum = 0
17 
18 func findTilt(_ root: TreeNode?) -> Int {
19         traverse(root)
20         return sum
21     }
22     
23     func traverse(_ root: TreeNode?) -> Int {
24         guard let root = root else {
25             return 0
26         }
27         var left = traverse(root.left)
28         var val = root.val
29         let right = traverse(root.right)
30         sum += Int(abs(left - right))
31         return left + right + val
32     }
33 }

---

128ms

 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(_ val: Int) {
 8  *         self.val = val
 9  *         self.left = nil
10  *         self.right = nil
11  *     }
12  * }
13  */
14 class Solution {
15     
16     var sum = 0
17 
18 func findTilt(_ root: TreeNode?) -> Int {
19         traverse(root)
20         return sum
21     }
22     
23     func traverse(_ root: TreeNode?) -> Int {
24         guard let root = root else {
25             return 0
26         }
27         var left = traverse(root.left)
28         var val = root.val
29         let right = traverse(root.right)
30         if (val == 1) {
31             print(left)
32             print(abs(left - right))
33         }
34         sum += Int(abs(left - right))
35         if (val == 2) {
36             print(left + right + val)
37         }
38         return left + right + val
39     }
40 }