update 129

Author: novahe

leetcode/0129.Sum-Root-to-Leaf-Numbers/129. Sum Root to Leaf Numbers.go

@@ -1,9 +1,5 @@
 package leetcode
 
-import (
-	"strconv"
-)
-
 import (
 	"github.com/halfrost/LeetCode-Go/structures"
 )
@@ -21,29 +17,20 @@ type TreeNode = structures.TreeNode
  */
 
 func sumNumbers(root *TreeNode) int {
-	res, nums := 0, binaryTreeNums(root)
-	for _, n := range nums {
-		num, _ := strconv.Atoi(n)
-		res += num
-	}
+	res := 0
+	dfs(root, 0, &res)
 	return res
 }
 
-func binaryTreeNums(root *TreeNode) []string {
+func dfs(root *TreeNode, sum int, res *int) {
 	if root == nil {
-		return []string{}
+		return
 	}
-	res := []string{}
+	sum = sum*10 + root.Val
 	if root.Left == nil && root.Right == nil {
-		return []string{strconv.Itoa(root.Val)}
+		*res += sum
+		return
 	}
-	tmpLeft := binaryTreeNums(root.Left)
-	for i := 0; i < len(tmpLeft); i++ {
-		res = append(res, strconv.Itoa(root.Val)+tmpLeft[i])
-	}
-	tmpRight := binaryTreeNums(root.Right)
-	for i := 0; i < len(tmpRight); i++ {
-		res = append(res, strconv.Itoa(root.Val)+tmpRight[i])
-	}
-	return res
+	dfs(root.Left, sum, res)
+	dfs(root.Right, sum, res)
 }

leetcode/0129.Sum-Root-to-Leaf-Numbers/README.md

@@ -45,4 +45,4 @@ Find the total sum of all root-to-leaf numbers.
 
 ## 解题思路
 
-- 这一题是第 257 题的变形题，第 257 题要求输出每条从根节点到叶子节点的路径，这一题变成了把每一个从根节点到叶子节点的数字都串联起来，再累加每条路径，求出最后的总和。实际做题思路基本没变
+- 运用前序遍历的思想，当从根节点出发一直加到叶子节点，每个叶子节点汇总一次。

website/content/ChapterFour/0100~0199/0129.Sum-Root-to-Leaf-Numbers.md

@@ -55,9 +55,12 @@ Find the total sum of all root-to-leaf numbers.
 package leetcode
 
 import (
-	"strconv"
+	"github.com/halfrost/LeetCode-Go/structures"
 )
 
+// TreeNode define
+type TreeNode = structures.TreeNode
+
 /**
  * Definition for a binary tree node.
  * type TreeNode struct {
@@ -66,32 +69,24 @@ import (
  *     Right *TreeNode
  * }
  */
+
 func sumNumbers(root *TreeNode) int {
-	res, nums := 0, binaryTreeNums(root)
-	for _, n := range nums {
-		num, _ := strconv.Atoi(n)
-		res += num
-	}
+	res := 0
+	dfs(root,0,&res)
 	return res
 }
 
-func binaryTreeNums(root *TreeNode) []string {
-	if root == nil {
-		return []string{}
+func dfs(root *TreeNode,sum int,res *int)  {
+	if root == nil{
+		return
 	}
-	res := []string{}
-	if root.Left == nil && root.Right == nil {
-		return []string{strconv.Itoa(root.Val)}
+	sum = sum*10 + root.Val
+	if root.Left == nil && root.Right == nil{
+		*res += sum
+		return
 	}
-	tmpLeft := binaryTreeNums(root.Left)
-	for i := 0; i < len(tmpLeft); i++ {
-		res = append(res, strconv.Itoa(root.Val)+tmpLeft[i])
-	}
-	tmpRight := binaryTreeNums(root.Right)
-	for i := 0; i < len(tmpRight); i++ {
-		res = append(res, strconv.Itoa(root.Val)+tmpRight[i])
-	}
-	return res
+	dfs(root.Left,sum,res)
+	dfs(root.Right,sum,res)
 }
 
 ```