[LeetCode][JavaScript]Binary Tree Paths

Binary Tree Paths

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"]

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

 

 

---

 

 

树的遍历，一个递归搞定。

每个节点看看左右还有没有孩子，如果有就递归进去，否则是叶子节点，加入结果数组。

每次都加上"->value"，要加入结果数组的时候去掉最前面的"->"。

两道类似的题：

Path Sum : http://www.cnblogs.com/Liok3187/p/4869521.html

Path Sum II : http://www.cnblogs.com/Liok3187/p/4869538.html

/**
 * 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) {
    var res = [];
    if(root && root.val !== undefined){
        getPaths(root, "");
    }
    return res;

    function getPaths(node, path){
        var isLeaf = true;
        if(node.left){
            isLeaf = false;
            getPaths(node.left, path + "->" + node.val);
        }
        if(node.right){
            isLeaf = false;
            getPaths(node.right, path + "->" + node.val);
        }
        if(isLeaf){
            var tmp = path + "->" + node.val;
            res.push(tmp.substring(2, tmp.length));
        }
    }
};