剑指 Offer 34. 二叉树中和为某一值的路径
输入一棵二叉树和一个整数，打印出二叉树中节点值的和为输入整数的所有路径。从树的根节点开始往下一直到叶节点所经过的节点形成一条路径。
示例:
给定如下二叉树，以及目标和 sum = 22，5 / 4 8 / / 11 13 4/ /
7 2 5 1
返回:[
[5,4,11,2],
[5,8,4,5]
]
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func pathSum(root *TreeNode, sum int) [][]int {
res := make([][]int, 0)
path := make([]int, 0)
if (root != nil) {
dfs(root, sum, path, &res)
}
return res
}
func dfs(root *TreeNode, sum int, path []int, res *[][]int) {
path = append(path, root.Val)
sum -= root.Val
if root.Left == nil && root.Right == nil {
if sum == 0 {
validPath := make([]int, len(path))
//注意对slice（引用类型）进行值copy
copy(validPath, path)
(*res) = append((*res), validPath)
}
} else {
if root.Left != nil {dfs(root.Left, sum, path, res)}
if root.Right != nil {dfs(root.Right, sum, path, res)}
}
path = path[0: len(path)-1]
}