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q0129.swift
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q0129.swift
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//
// q0129.swift
// LeetcodeSwift
//
// Created by NowOrNever on 25/06/2020.
// Copyright © 2020 DL. All rights reserved.
//
import Foundation
//129. Sum Root to Leaf Numbers
//Medium
//
//1246
//
//40
//
//Add to List
//
//Share
//Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.
//
//An example is the root-to-leaf path 1->2->3 which represents the number 123.
//
//Find the total sum of all root-to-leaf numbers.
//
//Note: A leaf is a node with no children.
//
//Example:
//
//Input: [1,2,3]
// 1
// / \
// 2 3
//Output: 25
//Explanation:
//The root-to-leaf path 1->2 represents the number 12.
//The root-to-leaf path 1->3 represents the number 13.
//Therefore, sum = 12 + 13 = 25.
//Example 2:
//
//Input: [4,9,0,5,1]
// 4
// / \
// 9 0
// / \
//5 1
//Output: 1026
//Explanation:
//The root-to-leaf path 4->9->5 represents the number 495.
//The root-to-leaf path 4->9->1 represents the number 491.
//The root-to-leaf path 4->0 represents the number 40.
//Therefore, sum = 495 + 491 + 40 = 1026.
//Accepted
//245,361
//Submissions
//522,723
class q0129Solution {
func sumNumbers_helper(_ node: TreeNode?, preNumber:Int, sum: inout Int){
guard let node = node else {
return
}
var nums = [Int]()
var temp = node.val
nums.append(temp % 10)
temp /= 10
while temp > 0 {
nums.append(temp % 10)
temp /= 10
}
var newPreNumber = preNumber
while nums.count > 0 {
newPreNumber = newPreNumber * 10 + nums.last!
nums.removeLast()
}
if node.left == nil && node.right == nil {
sum += newPreNumber
}else{
sumNumbers_helper(node.left, preNumber: newPreNumber, sum: &sum)
sumNumbers_helper(node.right, preNumber: newPreNumber, sum: &sum)
}
}
func sumNumbers(_ root: TreeNode?) -> Int {
var result = 0
sumNumbers_helper(root, preNumber: 0, sum: &result)
return result
}
}