手撸 golang 根本数据结构与算法 数组

缘起

最近浏览 << 我的第一本算法书 >>(【日】石田保辉；宫崎修一)
本系列笔记拟采纳 golang 练习之

数组

 数组是一种线性数据结构,
数据按顺序存储在内存的间断空间内。每个数据的内存地址（在内存上的地位）都能够通过数组下标算出，咱们也就能够借此间接拜访指标数据（这叫作“随机拜访”）。拜访数据时应用的是随机拜访（通过下标可计算出内存地址），所以须要的运行工夫仅为恒定的 O(1)。但另一方面，想要向数组中增加新数据时，必须把指标地位前面的数据一个个移开。所以，如果在数组头部增加数据，就须要 O(n) 的工夫。删除操作同理。摘自 << 我的第一本算法书 >>(【日】石田保辉；宫崎修一)

指标

• golang 自带数组和 slice, 但操作方法不够 OO, 本练习拟创立更 OO 的数组接口和办法

设计

• IArray: 定义数组的接口
• IArrayIterator: 定义数组的迭代器
• tCustomArray: 数组的 OO 封装, 实现 IArray 接口
• tArrayIterator: 数组迭代器, 实现 IArrayIterator 接口

单元测试

array_test.go

package data_structure

import (
    "learning/gooop/data_structure/array"
    "testing"
)

func Test_Array(t *testing.T) {fnAssertTrue := func(b bool, msg string) {
        if !b {t.Fatal(msg)
        }
    }

    it := array.NewArray()
    t.Log(it.String())
    fnAssertTrue(it.String() == "[]", "expecting []")

    it.Append(1)
    t.Log(it.String())
    fnAssertTrue(it.String() == "[1]", "expecting [1]")

    e := it.Remove(0)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[]", "expecting []")

    e = it.Insert(0, 1)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[1]", "expecting [1]")

    e = it.Insert(0, 0)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[0,1]", "expecting [0,1]")

    e = it.Insert(2, 2)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[0,1,2]", "expecting [0,1,2]")

    e = it.Set(0, 10)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[10,1,2]", "expecting [10,1,2]")

    e = it.Set(2, 20)
    t.Log(it.String())
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(it.String() == "[10,1,20]", "expecting [10,1,20]")

    e,x := it.Get(0)
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(x == 10, "expecting 10")

    e,x = it.Get(2)
    fnAssertTrue(e == nil, "expecting e == nil")
    fnAssertTrue(x == 20, "expecting 20")

    e,_ = it.Get(3)
    fnAssertTrue(e != nil, "expecting e != nil")

    e,_ = it.Get(-1)
    fnAssertTrue(e != nil, "expecting e != nil")
}

测试输入

$ go test -v array_test.go 
=== RUN   Test_Array
    array_test.go:16: []
    array_test.go:20: [1]
    array_test.go:24: []
    array_test.go:29: [1]
    array_test.go:34: [0,1]
    array_test.go:39: [0,1,2]
    array_test.go:44: [10,1,2]
    array_test.go:49: [10,1,20]
--- PASS: Test_Array (0.00s)
PASS
ok      command-line-arguments  0.002s

IArray.go

定义数组的接口

package array

type IArray interface {Size() int
    IsEmpty() bool
    IsNotEmpty() bool

    Get(i int) (error,interface{})
    Set(i int, it interface{}) error

    Append(it interface{})
    Remove(i int) error
    Insert(i int, it interface{}) error
    Iterator() IArrayIterator

    String() string}

IArrayIterator.go

定义数组的迭代器

package array

type IArrayIterator interface {More() bool
    Next() (error,interface{})
}

tCustomArray.go

数组的 OO 封装, 实现 IArray 接口

package array

import (
    "errors"
    "fmt"
    "strings"
)

type tCustomArray struct {items []interface{}
    size int
}

var gIndexOutofBoundsError = errors.New("index out of bounds")

func NewArray() IArray {
    return &tCustomArray{items: make([]interface{}, 0),
        size: 0,
    }
}

func (me *tCustomArray) Size() int {return me.size}

func (me *tCustomArray) IsEmpty() bool {return me.size <= 0}

func (me *tCustomArray) IsNotEmpty() bool {return !me.IsEmpty()
}

func (me *tCustomArray) Get(i int) (error,interface{}) {
    if i >= me.size || i < 0 {return gIndexOutofBoundsError, nil}
    return nil, me.items[i]
}

func (me *tCustomArray) Set(i int, it interface{}) error {
    if i >= me.size || i < 0 {return gIndexOutofBoundsError}
    me.items[i] = it
    return nil
}

func (me *tCustomArray) Append(it interface{}) {me.items = append(me.items, it)
    me.size++
}

func (me *tCustomArray) Remove(i int) error {
    if i >= me.size || i < 0 {return gIndexOutofBoundsError}

    me.items = append(me.items[:i], me.items[i+1:]...)
    me.size--

    return nil
}


func (me *tCustomArray) Insert(i int, it interface{}) error {
    if i > me.size || i < 0 {return gIndexOutofBoundsError}

    newItems := make([]interface{}, 0)
    newItems = append(newItems, me.items[:i]...)
    newItems = append(newItems, it)
    newItems = append(newItems, me.items[i:]...)

    me.items = newItems
    me.size++
    return nil
}


func (me *tCustomArray) Iterator() IArrayIterator {return newArrayIterator(me.items)
}

func (me *tCustomArray) String() string {ss := make([]string, me.size)
    for i,it := range me.items {ss[i] = fmt.Sprintf("%v", it)
    }
    return fmt.Sprintf("[%s]", strings.Join(ss, ","))
}

tArrayIterator.go

数组迭代器, 实现 IArrayIterator 接口

package array

type tArrayIterator struct {items []interface{}
    count int
    pos int
}

func newArrayIterator(items []interface{}) IArrayIterator {size := len(items)
    copy := make([]interface{}, size)
    for i,it := range items {copy[i] = it
    }

    return &tArrayIterator{
        items: copy,
        count: size,
        pos: 0,
    }
}


func (me *tArrayIterator) More() bool {return me.pos < me.count}

func (me *tArrayIterator) Next() (error,interface{}) {
    if me.pos >= me.count {return gIndexOutofBoundsError, nil}

    n := me.pos
    me.pos++
    return nil, me.items[n]
}

(end)