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Commit a0e9e1a

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144 solved. (#47)
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‎README.md

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* [107. Binary Tree Level Order Traversal II](./src/0107_binary_tree_level_order_traversal_2/binary_tree_level_order_traversal2.go)   *`binary tree;`*   *`bfs`*
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* [111. Minimum Depth of Binary Tree](./src/0111_minimum_depth_of_binary_tree/minimum_depth_of_binary_tree.go)   *`binary tree;`*   *`dfs`*
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* [112. Path Sum](./src/0112_path_sum/path_sum.go)   *`binary tree;`*   *`dfs`*
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* [144. Binary Tree Preorder Traversal](src/0144_binary_tree_preorder_traversal/binary_tree_preorder_traversal.go)   *`binary tree;`*   *`pre-order traversal`*
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* [226. Invert Binary Tree](./src/0226_invert_binary_tree/invert_binary_tree.go)   *`binary tree;`*
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### Binary Search
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/*
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144. Binary Tree Preorder Traversal
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https://leetcode.com/problems/binary-tree-preorder-traversal/
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Given a binary tree, return the preorder traversal of its nodes' values.
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*/
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// time: 2019年01月06日
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package btpot
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// TreeNode Definition for a binary tree node.
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type TreeNode struct {
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Val int
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Left *TreeNode
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Right *TreeNode
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}
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// recursive
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// time complexity: O(n), where n is nodes numbers in the tree.
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// space complexity: O(h), where h is the height of the tree.
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func preorderTraversal(root *TreeNode) []int {
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if root == nil {
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return []int{}
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}
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if root.Left == nil && root.Right == nil {
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return []int{root.Val}
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}
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left := preorderTraversal(root.Left)
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right := preorderTraversal(root.Right)
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res := []int{root.Val}
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res = append(res, left...)
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res = append(res, right...)
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return res
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}
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// iterative
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// time complexity: O(n), where n is nodes numbers in the tree.
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// space complexity: O(h), where h is the height of the tree.
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func preorderTraversal1(root *TreeNode) []int {
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if root == nil {
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return []int{}
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}
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var stack []*TreeNode
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var res []int
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stack = append(stack, root)
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for len(stack) > 0 {
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node := stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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res = append(res, node.Val)
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if node.Right != nil {
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stack = append(stack, node.Right)
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}
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if node.Left != nil {
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stack = append(stack, node.Left)
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}
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}
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return res
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}
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package btpot
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import (
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"reflect"
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"testing"
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)
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func createBinaryTree(nums []int) *TreeNode {
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return performCreate(nums, 0)
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}
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func performCreate(nums []int, index int) *TreeNode {
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if index >= len(nums) {
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return nil
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}
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tree := TreeNode{Val: nums[index]}
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tree.Left = performCreate(nums, 2*index+1)
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tree.Right = performCreate(nums, 2*index+2)
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return &tree
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}
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func TestPreorderTraversal(t *testing.T) {
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testCases := []*TreeNode{
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nil,
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createBinaryTree([]int{1, 2, 3, 4, 5, 6, 7, 8}),
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}
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expected := [][]int{
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{},
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{1, 2, 4, 8, 5, 3, 6, 7},
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}
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testFuncs := []func(node *TreeNode) []int{
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preorderTraversal,
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preorderTraversal1,
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}
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for _, testFunc := range testFuncs {
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for index, root := range testCases {
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if res := testFunc(root); !reflect.DeepEqual(res, expected[index]) {
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t.Errorf("expected %v, got %v", expected[index], res)
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}
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}
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}
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}

‎src/README.md

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|0121|[121. Best Time to Buy and Sell Stock](0121_best_time_to_buy_and_sell_stock/maxprofit.go)|Easy||
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|0122|[122. Best Time to Buy and Sell Stock II](0122_best_time_to_buy_and_sell_stock_2/maxprofit.go)|Easy|*`greedy`*|
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|0125|[Valid Palindrome](0125_valid_palindrome/valid_palindrome.go)|Easy||
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|0144|[144. Binary Tree Preorder Traversal](0144_binary_tree_preorder_traversal/binary_tree_preorder_traversal.go)|Medium|*`binary tree`*|
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|0167|[Two Sum II - Input array is sorted](./0167_two_sum2/two_sum2.go)|Easy|*`对撞指针(双索引)`*|
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|0198|[House Robber](./0198_house_robber/house_robber.go)|Easy|*`memory search;`* *`dynamic programming`*|
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|0209|[Minimum Size Subarray Sum](./0209_minimum_size_subarray_sum/minimum_size_subarray_sum.go)|Medium|*`sliding window`*|

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