date: 2019-03-21 21:30:00
本文为2019春节期间用golang刷LeetCode时遇到的基础使用方式，备注一下，后续可直接复制取用。
array
package main
import "fmt"
func main() {
//dealare way1
var arr1 [5]int //可以认为[5]int是一种类型
fmt.Println(arr1)
//dealare way2
arr2 := [...]int{1,2,3,4,5}
fmt.Println(arr2)
//dealare way3
arr3 := new([5]int) //得到指向数组的指针
fmt.Println(arr3)
//traversing way1
for j := 0; j < len(arr2); j++ {
fmt.Println(arr2[j])
}
//traversing way2
for i,_ := range arr3 {
fmt.Println(arr3[i])
}
}
heap
package main
import "fmt"
import "container/heap"
type IntHeap []int
func (h IntHeap) Len() int { return len(h) }
func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] }
func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
func (h *IntHeap) Push(x interface{}) {
*h = append(*h, x.(int))
}
func (h *IntHeap) Pop() interface{} {
old := *h
n := len(old)
x := old[n-1]
*h = old[0 : n-1]
return x
}
func main() {
h := &IntHeap{2, 1, 5}
heap.Init(h)
heap.Push(h, 0)
heap.Push(h, 6)
fmt.Println(h)
fmt.Println(h)
fmt.Println(h)
heap.Push(h, 1)
fmt.Println(h)
fmt.Println(h)
}
make
package main
import "fmt"
func main() {
//array 两种声明方式一样,都会开辟内存空间
var a1 [5]int
a2 := [5]int{}
a1[0] = 1
a2[0] = 1
fmt.Println(a1)
fmt.Println(a2)
//slice var不会开辟内存空间;:=如果传入值就会开辟，否则不开辟;make会开辟指定大小的内存空间;只有make的能直接赋值
var s1 []int
s2 := []int{}
s3 := make([]int, 5)
fmt.Println(s1)
fmt.Println(s2)
fmt.Println(s3)
//map 同slice;var 不能直接赋值;:=的可以直接赋值
var m1 map[int]int
m2 := map[int]int{}
m2[1]=3
m3 := make(map[int]int, 5)
m3[1]=2
fmt.Println(m1)
fmt.Println(m2)
fmt.Println(m3)
}
map
package main
import "fmt"
func main() {
//map 同slice;var 不能直接赋值;:=的可以直接赋值
var m1 map[int]int
m2 := map[int]int{}
m2[1]=3
m3 := make(map[int]int, 5)
m3[1]=2
fmt.Println(m1)
fmt.Println(m2)
fmt.Println(m3)
//判断map中某个元素是否存在
if _, ok := map[key]; ok {
//存在
}
}
queue
package main
import "fmt"
//实现一个队列
type queue struct {
val []int
}
func (this *queue) push(val int) {
this.val = append(this.val, val)
}
func (this *queue) pop() int {
result := this.val[0]
this.val = this.val[1:]
return result
}
func (this *queue) peek() int {
return this.val[0]
}
func (this *queue) size() int {
return len(this.val)
}
func (this *queue) empty() bool {
if (0 == len(this.val)) {
return true
}
return false
}
//实现队列结束
func main() {
queue := queue{[]int{}} //{}是初始化一个结构体,[]int{}是传入的值
queue.push(1)
queue.push(2)
queue.push(3)
fmt.Println(queue.pop())
fmt.Println(queue.pop())
fmt.Println(queue.pop())
}
slice
package main
import "fmt"
func main() {
//relation of slice and array
//slice is a reference of array
//array := [5]int{1,2,3,4,5}
//slice := array[:]
//fmt.Println(array)
//fmt.Println(slice)
//declare way1
var slice1 []int //len = 0 and cap = 0
fmt.Println(slice1)
//declare way2
slice2 := []int {1,2,3,4,5} //len = 5 and cap = 5
fmt.Println(slice2)
//declare and create : make ; make will create slice and slice's relation array
slice3 := make([]int, 10) //len = 10 and cap = 10
slice4 := make([]int, 10, 20) //len = 10 and cap = 20
fmt.Println(slice3)
fmt.Println(slice4)
//declare and create : new ;
slice5 := new([100]int)[0:30] //"new" allocate memory of array and assignment array's slices to slice5
fmt.Println(slice5)
//deferent between new and make : "new" allocate memory for type T and return the address of *T ; "make" create a object of type T and return it
//slice use
fmt.Println(slice2[0:3])
fmt.Println(slice2[3:])
fmt.Println(slice2[:3])
}
stack
package main
import "fmt"
//实现一个栈
type stack struct {
val []interface{}
}
func (this *stack) push(val interface{}) {
this.val = append([]interface{}{val}, this.val...)
}
func (this *stack) pop() interface{} {
result := this.val[0]
this.val = this.val[1:]
return result
}
func (this *stack) peek() interface{} {
return this.val[0]
}
func (this *stack) size() interface{} {
return len(this.val)
}
func (this *stack) empty() bool {
if (0 == len(this.val)) {
return true
}
return false
}
//实现栈结束
func main() {
var stack stack
stack.push(1)
stack.push(2)
stack.push(3)
fmt.Println(stack.pop())
fmt.Println(stack.pop())
fmt.Println(stack.pop())
}
string
package main
import "fmt"
import "strings"
import "strconv"
func main() {
// string 是[]byte的别名
// byte是uint8的别名,用来表示ascii;一个英文字符对应一个byte,一个中文字符对应三个byte
// rune是int32的别名,用来表示utf-8[一个中文占三个字节]/unicode[一个中文占两个字节];一个rune对应一个UTF-8字符
str := "中文test string"
fmt.Println("str[0]:", str[0])
// = string转[]byte,其实不转也是
strByte := []byte(str)
fmt.Println("strByte[0]:", strByte[0])
// = string转[]rune
strRune := []rune(str)
fmt.Println("strRune[0]:", strRune[0])
// = string求长度
fmt.Println("strings.Count()-1:", strings.Count(str, "")-1)
// = string切割
fmt.Println("strings.Split", strings.Split(str, ""))
// = string截取
fmt.Println("str[:]", str[6:])
// = string转int
if strToNumber, err := strconv.Atoi("1"); err == nil {
fmt.Println("strconv.Atoi()", strToNumber)
}
// = int转string
fmt.Println("strconv.Itoa()", strconv.Itoa(1))
}
struct
package main
import "fmt"
type man struct {
name string
age int
weight int
score []int
}
func main() {
//创建结构体的方法1
var qiao man //qiao的类型是man
qiao.name = "qiao"
qiao.age = 25
qiao.weight = 140
qiao.score = append(qiao.score, 1)
qiao.score = append(qiao.score, 2)
fmt.Println(qiao)
//创建结构体的方法2
yang := new(man) //yang的类型是指向man类型实例的指针
yang.name = "yang"
fmt.Println(yang)
//创建结构体的方法3
liu := man{}
fmt.Println(liu)
zhang := man{"zhang", 25, 140, []int{1,2,3,4,5}}
fmt.Println(zhang)
//创建结构体的方法4
li := &man{}
fmt.Println(liu)
zhang := man{"zhang", 25, 140, []int{1,2,3,4,5}}
fmt.Println(zhang)
//创建结构体的方法4
li := &man{}
fmt.Println(li)
}
传值还是传指针
package main
import "fmt"
func main() {
// int/float/bool/string/array 值类型
// slice/map 指针类型
i := 1; f := 1.1; b := true; s := "a"
testBaseType(i, f, b , s)
fmt.Println(i, f, b , s)
arr := [...]int{1,1,1}; sli := []int{1,1,1}; m := map[int]int{1:1,2:2};
testSeniorType(arr, sli, m)
fmt.Println(arr, sli, m)
}
func testBaseType(i int, f float64, b bool, s string) {
i = 2
f = 2.2
b = false
s = "b"
}
func testSeniorType(arr [3]int, sli []int, m map[int]int) {
arr[0] = 2
sliCopy := make([]int, len(sli))
copy(sliCopy, sli)
sliCopy[0] = 2
m[1] = 2
}
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