golang基础-排序、二分查找、map、map排序反转

排序

package main

import(
    "fmt"
    "sort"
)

func main() {
    testInSort()
    testString()
    testFloat()
}

func testFloat(){
    var a = [...]float64{12.5,455.677,236.77,-234.66,0,5.99}
    sort.Float64s(a[:])
    fmt.Println(a)
}

func testString(){
    var a = [...]string{"wefD","wefghn","thGw","wGGef","sfsf"}
    sort.Strings(a[:])
    fmt.Println(a)
}

/*数组是值类型，如果要改变值，需要传切片进去，去改变*/
func testInSort(){

    var a = [...]int{1,3,5,-5,-4}
    //需要传递切片进去才能排序
    sort.Ints(a[:])
    fmt.Println(a)


}

输出如下：

PS E:golanggo_prosrcsafly> go run demo.go
[-5 -4 0 1 3 5]
[sfsf thGw wGGef wefD wefghn]
[-234.66 0 5.99 12.5 236.77 455.677]
PS E:golanggo_prosrcsafly>

二分查找

ort.SearchInts(a []int,b int) 从数组a中查找b，前提是a必须有序
sort.SearchFloats(a []float64,b float64) 从数组a中查找b，前提是a必须有序
sort.SearchStrings(a []string,b string) 从数组a中查找b，前提是a必须有序

package main

import(
    "fmt"
    "sort"
)

func main() {
    testSearchIn()

} //从数组a中查找b，前提是a必须有序
func testSearchIn(){
    var a = [...] int {1,8,38,2,348,484,-6}
    //没有排序直接进行查找
    index:= sort.SearchInts(a[:],2)
    //输出1是错误的，因为没有排序
    fmt.Println(index)

    //进行排序操作
    sort.Ints(a[:])
    fmt.Println(a)
    //传切片过去
    index= sort.SearchInts(a[:],2)
    fmt.Println(index)

}

输出如下：

PS E:golanggo_prosrcsafly> go run demo.go
1
[-6 1 2 8 38 348 484]
2
PS E:golanggo_prosrcsafly>

map

map创建方式

package main

import(
    "fmt"
)


func main() {
    testMap()
    testMoreMap()
}

//map嵌套
func testMoreMap(){

    a:= make(map[string]map[string]string,100)
    //value是map，使用时候需要为其开辟空间
    a["k1"] = make(map[string]string)
    a["k1"]["k1k1"]= "aaa"
    fmt.Println(a)
}

//创建map的2种方式
func testMap(){
     a  := make(map[string]string,10)
    a["abc"] = "abc"
    fmt.Println(a)

    var b map[string] string = map[string]string{
        "bcd":"bcd",}
    fmt.Println(b)
}

输出如下：

PS E:golanggo_prosrcsafly> go run demo.go
map[abc:abc]
map[bcd:bcd]
map[k1:map[k1k1:aaa]]
PS E:golanggo_prosrcsafly>

map循环遍历

package main

import(
    "fmt"
)


func main() {
    testMap3()
    fmt.Println("---------------")
    testMap4()
    testMap5()
}
/*切片里面是map*/
func testMap5() {
    var a []map[int]int
    a = make([]map[int]int, 5)

    if a[0] == nil {
        a[0] = make(map[int]int)
    }
    a[0][10] = 10
    fmt.Println(a)
}
/*循环遍历*/
func testMap4(){
    a:= make(map[string]map[string]string,100)
    a["k1"] = make(map[string]string)
    a["k1"]["k2"] = "abc"
    a["k1"]["k3"] = "bcd"

    a["k2"] = make(map[string]string)
    a["k2"]["k4"] = "efg"
    a["k2"]["k5"] = "hij"

    for k,v := range a{
        fmt.Println(k)
        for k1,v1:= range v{
            fmt.Println(k1,v1)
        }
    }

    //删除
    fmt.Println("-------删除前后-------")
    delete(a,"k1")
    for k,v1)
        }
    }
 }


func testMap3(){
    a := make(map[string]map[string]string,10)
    modify(a)
    fmt.Println(a)
}

func modify(a map[string]map[string]string){
    _,ok:=a["zhangsan"]
    //输出false
    fmt.Println(ok)
    if !ok {
        a["zhangsan"] = make(map[string]string)
    }
    a["zhangsan"]["pass"] = "123"
    return
}

输出如下：

PS E:golanggo_prosrcsafly> go run demo.go
false
map[zhangsan:map[pass:123]]
---------------
k1
k2 abc
k3 bcd
k2
k4 efg
k5 hij
-------删除前后-------
k2
k4 efg
k5 hij
[map[10:10] map[] map[] map[] map[]]
PS E:golanggo_prosrcsafly>

排序、反转

package main

import(
    "fmt"
    "sort"
)


func testMapReverse(){
    var a map[int]string 
    var b map[string] int
    a = make(map[int]string,5)
    b = make(map[string] int ,5)

    a[1] = "a"
    a[2] = "b"

    for k,v := range a{
        b[v] = k
    }
    for k,v := range b{
        fmt.Println(k,v)
    }

}
func main() {

    testMapSort()
    fmt.Println("--------")
    testMapReverse()
}

func testMapSort(){
    var a map[int]int 
    a = make(map[int]int ,8)
    a[1] = 10
    a[2] = 11
    a[3] = 12
    a[4] = 13
    //定义一个切片
    var b []int
    //说明map是无序的
    for k,v := range a{
        fmt.Println(k,v)
        b = append(b,v)
    }

    sort.Ints(b)
    fmt.Println("----------对map的值进行排序（放到切片里面）-----------")
    for k,v:= range b{
        fmt.Println(k,v)
    }
}

输出如下：

PS E:golanggo_prosrcsafly> go run demo.go
1 10
2 11
3 12
4 13
----------对map的值进行排序（放到切片里面）-----------
0 10
1 11
2 12
3 13
--------
b 2
a 1
PS E:golanggo_prosrcsafly>