Created
December 5, 2016 23:38
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postorderTraversal
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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 {number[]} | |
| */ | |
| var postorderTraversal = function(root) { | |
| var stack = root ? [root] : []; | |
| var prev = null; | |
| var res = []; | |
| while(stack.length > 0) { | |
| var node = stack.pop(); | |
| var visit = node; | |
| if(!node.left) { | |
| visit = prev === node.right ? node : node.right; | |
| } | |
| else if(!prev || prev !== node.right){ | |
| visit = prev === node.left ? node.right : node.left; | |
| } | |
| if(visit && visit !== node) { | |
| stack.push(node); | |
| stack.push(visit); | |
| } | |
| else { | |
| res.push(node.val); | |
| } | |
| prev = node; | |
| } | |
| return res; | |
| }; |
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