从零开始Leetcode – Day 16
Flatten Binary Tree to Linked List
https://leetcode.com/problems/flatten-binary-tree-to-linked-list/
1 注意考虑起始条件， 和终止条件。
2 晚上做不了算法题， 白天做过的，到了晚上不能debug.
3 所有题目要重做一次， 才会产生效果。
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| /**
* Definition for a binary tree node.
* function TreeNode(val) {
* this.val = val;
* this.left = this.right = null;
* }
*/
/**
* @param {TreeNode} root
* @return {void} Do not return anything, modify root in-place instead.
*/
var flatten = function(root) {
var pre = [];
pre.push(null);
helper(root, pre);
};
var helper = function(root, pre){
if(root ===null){
return;
}
var right = new TreeNode();
right = root.right;
if(pre[0] !== null){
pre[0].left = null;
pre[0].right = root;
}
pre.unshift(root);
helper(root.left, pre);
helper(right, pre);
};
|