[LeetCode By Go 86]257. Binary Tree Paths

题目

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

   1
 /   \
2     3
 \
  5

All root-to-leaf paths are:

[“1->2->5”, “1->3”]

解题思路

使用递归解题,递归的过程中记录当前的路径,找到叶子节点后将路径放入结果数组中,在递归过程中:

  1. 如果左右子节点都为空指针,则说明当前节点为二叉树的叶子,获得一条路径,将这条路径加入结果数组中
  2. 否则分别判断左右子节点是否为空,如果不为空,则进行递归继续寻找其路径

代码

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
var ret []string

func getPath(t *TreeNode, s string)  {
    val := t.Val
    s = s + "->" + strconv.Itoa(val)
    
    if nil == t.Left && nil == t.Right {
        ret = append(ret, s)
    }
    if nil != t.Left {
        getPath(t.Left, s)
    }
    if nil != t.Right {
        getPath(t.Right, s)
    }
}

func binaryTreePaths(root *TreeNode) []string {
    ret = []string{}
    if nil == root {
        return ret
    }

    rootval := root.Val
    
    if nil == root.Left && nil == root.Right {
        ret = append(ret, strconv.Itoa(rootval))
        return ret 
    } 
    if nil != root.Left {
        getPath(root.Left, strconv.Itoa(rootval))
    } 
    if nil != root.Right {
        getPath(root.Right, strconv.Itoa(rootval))
    }
    

    return ret
}
    原文作者:miltonsun
    原文地址: https://www.jianshu.com/p/763a2afbd82c
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