二叉树的所有路径

输入:

   1
 /   \
2     3
 \
  5

输出: ["1->2->5", "1->3"]

解释: 所有根节点到叶子节点的路径为: 1->2->5, 1->3

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {string[]}
 */
var binaryTreePaths = function(root) {
    if(!root) return [];
    var target = [];
    var dfs = function(root, tmp){
        if(!root) return void 0;
        if(!root.left && !root.right){
            target.push(tmp);
            return void 0;
        }
        if(root.left) dfs(root.left, `${tmp}->${root.left.val}`);
        if(root.right) dfs(root.right, `${tmp}->${root.right.val}`);
    }
    dfs(root, `${root.val}`)
    return target;
};

https://github.com/WindrunnerMax/EveryDay

https://leetcode-cn.com/problems/binary-tree-paths