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Merge pull request krahets#119 from Cathay-Chen/master
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Add the Go code to space complexity docs
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@krahets
krahets authored Dec 15, 2022
2 parents b3d642f + ae37e90 commit 133955c
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123 changes: 123 additions & 0 deletions codes/go/chapter_computational_complexity/space_complexity.go
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// File: space_complexity.go
// Created Time: 2022-12-15
// Author: cathay ([email protected])

package chapter_computational_complexity

import (
"fmt"
"strconv"
)

/* Node 结构体 */
type Node struct {
val int
next *Node
}

/* TreeNode 二叉树 */
type TreeNode struct {
val int
left *TreeNode
right *TreeNode
}

/* 创建 Node 结构体 */
func newNode(val int) *Node {
return &Node{val: val}
}

/* 创建 TreeNode 结构体 */
func newTreeNode(val int) *TreeNode {
return &TreeNode{val: val}
}

/* 输出二叉树 */
func printTree(root *TreeNode) {
if root == nil {
return
}
fmt.Println(root.val)
printTree(root.left)
printTree(root.right)
}

/* 函数（或称方法）*/
func function() int {
// do something...
return 0
}

/* 常数阶 */
func spaceConstant(n int) {
// 常量、变量、对象占用 O(1) 空间
const a = 0
b := 0
nums := make([]int, 10000)
ListNode := newNode(0)
// 循环中的变量占用 O(1) 空间
var c int
for i := 0; i < n; i++ {
c = 0
}
// 循环中的函数占用 O(1) 空间
for i := 0; i < n; i++ {
function()
}
fmt.Println(a, b, nums, c, ListNode)
}

/* 线性阶 */
func spaceLinear(n int) {
// 长度为 n 的数组占用 O(n) 空间
_ = make([]int, n)
// 长度为 n 的列表占用 O(n) 空间
var nodes []*Node
for i := 0; i < n; i++ {
nodes = append(nodes, newNode(i))
}
// 长度为 n 的哈希表占用 O(n) 空间
m := make(map[int]string, n)
for i := 0; i < n; i++ {
m[i] = strconv.Itoa(i)
}
}

/* 线性阶（递归实现） */
func spaceLinearRecur(n int) {
fmt.Println("递归 n =", n)
if n == 1 {
return
}
spaceLinearRecur(n - 1)
}

/* 平方阶 */
func spaceQuadratic(n int) {
// 矩阵占用 O(n^2) 空间
numMatrix := make([][]int, n)
for i := 0; i < n; i++ {
numMatrix[i] = make([]int, n)
}
}

/* 平方阶（递归实现） */
func spaceQuadraticRecur(n int) int {
if n <= 0 {
return 0
}
nums := make([]int, n)
fmt.Printf("递归 n = %d 中的 nums 长度 = %d \n", n, len(nums))
return spaceQuadraticRecur(n - 1)
}

/* 指数阶（建立满二叉树） */
func buildTree(n int) *TreeNode {
if n == 0 {
return nil
}
root := newTreeNode(0)
root.left = buildTree(n - 1)
root.right = buildTree(n - 1)
return root
}
30 changes: 30 additions & 0 deletions codes/go/chapter_computational_complexity/space_complexity_test.go
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// File: space_complexity_test.go
// Created Time: 2022-12-15
// Author: cathay ([email protected])

package chapter_computational_complexity

import (
"testing"
)

func TestSpaceComplexity(t *testing.T) {
/* ======= Test Case ======= */
n := 5

/* ====== Driver Code ====== */
// 常数阶
spaceConstant(n)

// 线性阶
spaceLinear(n)
spaceLinearRecur(n)

// 平方阶
spaceQuadratic(n)
spaceQuadraticRecur(n)

// 指数阶
root := buildTree(n)
printTree(root)
}
127 changes: 119 additions & 8 deletions docs/chapter_computational_complexity/space_complexity.md
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Expand Up @@ -102,7 +102,30 @@ comments: true
=== "Go"

```go title=""
/* 结构体 */
type Node struct {
val int
next *Node
}

/* 创建 Node 结构体 */
func newNode(val int) *Node {
return &Node{val: val}
}

/* 函数（或称方法）*/
func function() int {
// do something...
return 0
}

func algorithm(n int) int { // 输入数据
const a = 0 // 暂存数据（常量）
b := 0 // 暂存数据（变量）
newNode(0) // 暂存数据（对象）
c := function() // 栈帧空间（调用函数）
return a + b + c // 输出数据
}
```

=== "JavaScript"
Expand Down Expand Up @@ -173,7 +196,15 @@ comments: true
=== "Go"

```go title=""

func algorithm(n int) {
a := 0 // O(1)
b := make([]int, 10000) // O(1)
var nums []int
if n > 10 {
nums = make([]int, 10000) // O(n)
}
fmt.Println(a, b, nums)
}
```

=== "JavaScript"
Expand Down Expand Up @@ -263,7 +294,25 @@ comments: true
=== "Go"

```go title=""

func function() int {
// do something
return 0
}

/* 循环 O(1) */
func loop(n int) {
for i := 0; i < n; i++ {
function()
}
}

/* 递归 O(n) */
func recur(n int) {
if n == 1 {
return
}
recur(n - 1)
}
```

=== "JavaScript"
Expand Down Expand Up @@ -377,7 +426,24 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 常数阶 */
func spaceConstant(n int) {
// 常量、变量、对象占用 O(1) 空间
const a = 0
b := 0
nums := make([]int, 10000)
ListNode := newNode(0)
// 循环中的变量占用 O(1) 空间
var c int
for i := 0; i < n; i++ {
c = 0
}
// 循环中的函数占用 O(1) 空间
for i := 0; i < n; i++ {
function()
}
fmt.Println(a, b, nums, c, ListNode)
}
```

=== "JavaScript"
Expand Down Expand Up @@ -464,7 +530,21 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 线性阶 */
func spaceLinear(n int) {
// 长度为 n 的数组占用 O(n) 空间
_ = make([]int, n)
// 长度为 n 的列表占用 O(n) 空间
var nodes []*Node
for i := 0; i < n; i++ {
nodes = append(nodes, newNode(i))
}
// 长度为 n 的哈希表占用 O(n) 空间
m := make(map[int]string, n)
for i := 0; i < n; i++ {
m[i] = strconv.Itoa(i)
}
}
```

=== "JavaScript"
Expand Down Expand Up @@ -528,7 +608,14 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 线性阶（递归实现） */
func spaceLinearRecur(n int) {
fmt.Println("递归 n =", n)
if n == 1 {
return
}
spaceLinearRecur(n - 1)
}
```

=== "JavaScript"
Expand Down Expand Up @@ -611,7 +698,14 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 平方阶 */
func spaceQuadratic(n int) {
// 矩阵占用 O(n^2) 空间
numMatrix := make([][]int, n)
for i := 0; i < n; i++ {
numMatrix[i] = make([]int, n)
}
}
```

=== "JavaScript"
Expand Down Expand Up @@ -678,7 +772,15 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 平方阶（递归实现） */
func spaceQuadraticRecur(n int) int {
if n <= 0 {
return 0
}
nums := make([]int, n)
fmt.Printf("递归 n = %d 中的 nums 长度 = %d \n", n, len(nums))
return spaceQuadraticRecur(n - 1)
}
```

=== "JavaScript"
Expand Down Expand Up @@ -754,7 +856,16 @@ $$
=== "Go"

```go title="space_complexity.go"

/* 指数阶（建立满二叉树） */
func buildTree(n int) *TreeNode {
if n == 0 {
return nil
}
root := newTreeNode(0)
root.left = buildTree(n - 1)
root.right = buildTree(n - 1)
return root
}
```

=== "JavaScript"
Expand Down

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