一个无聊男人的疯狂《数据结构与算法分析-C++描述》学习笔记 用C++/lua/python/bash的四重实现（7）习题2.8 随机数组的三种生成算法

--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;
mso-font-charset:2;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:0 268435456 0 0 -2147483648 0;}
@font-face
{font-family:宋体;
panose-1:2 1 6 0 3 1 1 1 1 1;
mso-font-alt:SimSun;
mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
@font-face
{font-family:Cambria;
panose-1:2 4 5 3 5 4 6 3 2 4;
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1073741899 0 0 159 0;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;
mso-font-charset:0;
mso-generic-font-family:swiss;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1073750139 0 0 159 0;}
@font-face
{font-family:"/@宋体";
panose-1:2 1 6 0 3 1 1 1 1 1;
mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
margin-top:0cm;
margin-right:0cm;
margin-bottom:10.0pt;
margin-left:0cm;
line-height:115%;
mso-pagination:widow-orphan;
font-size:12.0pt;
mso-bidi-font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
h1
{mso-style-priority:9;
mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-link:"标题 1 Char";
mso-style-next:正文;
margin-top:24.0pt;
margin-right:0cm;
margin-bottom:0cm;
margin-left:0cm;
margin-bottom:.0001pt;
line-height:115%;
mso-pagination:widow-orphan lines-together;
page-break-after:avoid;
mso-outline-level:1;
font-size:16.0pt;
mso-bidi-font-size:14.0pt;
font-family:"Cambria","serif";
mso-ascii-font-family:Cambria;
mso-ascii-theme-font:major-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:major-fareast;
mso-hansi-font-family:Cambria;
mso-hansi-theme-font:major-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:major-bidi;
color:#365F91;
mso-themecolor:accent1;
mso-themeshade:191;
mso-font-kerning:1.0pt;}
h2
{mso-style-priority:9;
mso-style-qformat:yes;
mso-style-link:"标题 2 Char";
mso-style-next:正文;
margin-top:13.0pt;
margin-right:0cm;
margin-bottom:13.0pt;
margin-left:0cm;
line-height:173%;
mso-pagination:widow-orphan lines-together;
page-break-after:avoid;
mso-outline-level:2;
font-size:16.0pt;
font-family:"Cambria","serif";
mso-ascii-font-family:Cambria;
mso-ascii-theme-font:major-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:major-fareast;
mso-hansi-font-family:Cambria;
mso-hansi-theme-font:major-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:major-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
p.MsoHeader, li.MsoHeader, div.MsoHeader
{mso-style-noshow:yes;
mso-style-priority:99;
mso-style-link:"页眉 Char";
margin-top:0cm;
margin-right:0cm;
margin-bottom:10.0pt;
margin-left:0cm;
text-align:center;
mso-pagination:widow-orphan;
tab-stops:center 207.65pt right 415.3pt;
layout-grid-mode:char;
border:none;
mso-border-bottom-alt:solid windowtext .75pt;
padding:0cm;
mso-padding-alt:0cm 0cm 1.0pt 0cm;
font-size:9.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
p.MsoFooter, li.MsoFooter, div.MsoFooter
{mso-style-noshow:yes;
mso-style-priority:99;
mso-style-link:"页脚 Char";
margin-top:0cm;
margin-right:0cm;
margin-bottom:10.0pt;
margin-left:0cm;
mso-pagination:widow-orphan;
tab-stops:center 207.65pt right 415.3pt;
layout-grid-mode:char;
font-size:9.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;
text-underline:single;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-noshow:yes;
mso-style-priority:99;
color:purple;
mso-themecolor:followedhyperlink;
text-decoration:underline;
text-underline:single;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-noshow:yes;
mso-style-priority:99;
mso-style-link:"批注框文本 Char";
margin:0cm;
margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:9.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
mso-style-unhide:no;
mso-style-qformat:yes;
margin-top:0cm;
margin-right:0cm;
margin-bottom:10.0pt;
margin-left:0cm;
text-indent:21.0pt;
mso-char-indent-count:2.0;
line-height:115%;
mso-pagination:widow-orphan;
font-size:12.0pt;
mso-bidi-font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
span.MsoIntenseReference
{mso-style-priority:32;
mso-style-unhide:no;
mso-style-qformat:yes;
font-variant:small-caps;
color:#C0504D;
mso-themecolor:accent2;
letter-spacing:.25pt;
font-weight:bold;
text-decoration:underline;
text-underline:single;}
span.1Char
{mso-style-name:"标题 1 Char";
mso-style-priority:9;
mso-style-unhide:no;
mso-style-locked:yes;
mso-style-link:"标题 1";
mso-ansi-font-size:16.0pt;
mso-bidi-font-size:14.0pt;
font-family:"Cambria","serif";
mso-ascii-font-family:Cambria;
mso-ascii-theme-font:major-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:major-fareast;
mso-hansi-font-family:Cambria;
mso-hansi-theme-font:major-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:major-bidi;
color:#365F91;
mso-themecolor:accent1;
mso-themeshade:191;
font-weight:bold;}
span.2Char
{mso-style-name:"标题 2 Char";
mso-style-priority:9;
mso-style-unhide:no;
mso-style-locked:yes;
mso-style-link:"标题 2";
mso-ansi-font-size:16.0pt;
mso-bidi-font-size:16.0pt;
font-family:"Cambria","serif";
mso-ascii-font-family:Cambria;
mso-ascii-theme-font:major-latin;
mso-fareast-font-family:宋体;
mso-fareast-theme-font:major-fareast;
mso-hansi-font-family:Cambria;
mso-hansi-theme-font:major-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:major-bidi;
mso-font-kerning:0pt;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;
font-weight:bold;}
span.Char
{mso-style-name:"页眉 Char";
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-unhide:no;
mso-style-locked:yes;
mso-style-link:页眉;
mso-ansi-font-size:9.0pt;
mso-bidi-font-size:9.0pt;
mso-font-kerning:0pt;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
span.Char0
{mso-style-name:"页脚 Char";
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-unhide:no;
mso-style-locked:yes;
mso-style-link:页脚;
mso-ansi-font-size:9.0pt;
mso-bidi-font-size:9.0pt;
mso-font-kerning:0pt;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
span.Char1
{mso-style-name:"批注框文本 Char";
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-unhide:no;
mso-style-locked:yes;
mso-style-link:批注框文本;
mso-ansi-font-size:9.0pt;
mso-bidi-font-size:9.0pt;
mso-font-kerning:0pt;
mso-fareast-language:EN-US;
mso-bidi-language:EN-US;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
{size:595.3pt 841.9pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;
mso-header-margin:42.55pt;
mso-footer-margin:49.6pt;
mso-paper-source:0;
layout-grid:15.6pt;}
div.Section1
{page:Section1;}
/* List Definitions */
@list l0
{mso-list-id:879979139;
mso-list-type:hybrid;
mso-list-template-ids:-2200530 -26160278 67698691 67698693 67698689 67698691 67698693 67698689 67698691 67698693;}
@list l0:level1
{mso-level-start-at:0;
mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
margin-left:18.0pt;
text-indent:-18.0pt;
font-family:Wingdings;
mso-fareast-font-family:宋体;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
@list l1
{mso-list-id:1980842703;
mso-list-type:hybrid;
mso-list-template-ids:310389072 -1595380626 67698691 67698693 67698689 67698691 67698693 67698689 67698691 67698693;}
@list l1:level1
{mso-level-start-at:0;
mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
margin-left:18.0pt;
text-indent:-18.0pt;
font-family:Wingdings;
mso-fareast-font-family:宋体;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
ol
{margin-bottom:0cm;}
ul
{margin-bottom:0cm;}
-->

一个无聊男人的疯狂《数据结构与算法分析-C++描述》学习笔记
用C++/lua/python/bash的四重实现（7）习题2.8 随机数组的三种生成算法

write by 九天雁翎(JTianLing) --
blog.csdn.net/vagrxie



<<Data Structures and Algorithm Analysis in C++>>

--《数据结构与算法分析c++描述》 Mark Allen Weiss著 人民邮电大学出版 中文版第49面， 一随机数组的三种生成算法

这一次没有截图，因为我受不了让bash运行100次的速度，怎么说来着，还是那句话，Bash根本就不适合也不是设计用来描述算法的语言，我根本就是自讨苦吃。用了最多的时间，得到的是最低的效率。。。。。。还有最扭曲的代码。但是因为工作中不用到bash，不常用用还真怕都忘了。。。现在用python的时候就常有这样的感觉，以前看的书就像白看了一样。

相对于bash来说，python的优雅一次一次的深入我心，每一次它都是代码最短的，最最优雅的，很多便捷的语法都是让人用的很痛快，虽然刚开始用的时候由于没有大括号。。。（我用c++习惯了）感觉代码就像悬在空中一样的不可靠。。。呵呵，习惯了以后，怎么看怎么爽。再加上丰富的库，绝了。



write by 九天雁翎(JTianLing)
-- blog.csdn.net/vagrxie

以下为实现部分:

CPP:

1
#include
<stdio.h>

2 #include
<stdlib.h>

3 #include
<algorithm>

4 #include
<iterator>

5 #include
<iostream>

6 using namespace std;

7

8 int randInt(int i, int j)

9 {

10 if(i > j)

11 {

12 int temp = i;

13 i
= j;

14 j
= temp;

15 }

16

17 return rand() % (j-i) + i;

18 }

19

20 void randArr1(int arr[], int n)

21 {

22 for(int i=0; i<n; ++i)

23 {

24 while(true)

25 {

26 // some thing don't like py

27 // because my randInt is create number

28 // in [0,n) and py is [0,n]

29 int temp = randInt(0, n);

30 int j = 0;

31 while(j < i)

32 {

33 if(arr[j] == temp)

34 {

35 break;

36 }

37 ++j;

38 }

39 if(j == i)

40 {

41 arr[j]
= temp;

42 break;

43 }

44 }

45 }

46 }

47

48 void randArr2(int a[], int n)

49 {

50 bool *lpb = new bool
;

51 memset(lpb,
0, n);

52

53 for(int i=0; i<n; ++i)

54 {

55 while(true)

56 {

57 int temp = randInt(0, n);

58 if(!lpb[temp])

59 {

60 a[i]
= temp;

61 lpb[temp]
= true;

62 break;

63 }

64 }

65

66 }

67

68 delete lpb;

69 lpb = NULL;

70 }

71

72 void swap(int& a, int&
b)

73 {

74 int temp = a;

75 a = b;

76 b = temp;

77 }

78

79 // just
for fun,but I like it.

80 // when py
could have range and bash could have seq

81 // why cpp
couldn't have a seq like this? lol

82 template<typename T>

83 class CFBSeq

84 {

85 public:

86 CFBSeq(const T& aValue) : mValue(aValue) {
}

87

88 T operator()()

89 {

90 return mValue++;

91 }

92

93 private:

94 T mValue;

95 };

96

97 void randArr3(int a[], int n)

98 {

99 generate(a,
a+n, CFBSeq<int>(0));

100

101 for(int i=1; i<n; ++i)

102 {

103 swap(a[i],
a[randInt(0,i)]);

104 }

105

106 }

107

108

109

110

111

112 int main(int argc, char*
argv[])

113 {

114 const int TIMES=100;

115 srand(time(NULL));

116 int a[TIMES],b[TIMES],c[TIMES];

117 randArr1(a,TIMES);

118 copy(a, a+TIMES,
ostream_iterator<int>(cout," "));

119 printf("/n");

120 randArr2(b,TIMES);

121 copy(b, b+TIMES,
ostream_iterator<int>(cout," "));

122 printf("/n");

123 randArr3(c,
TIMES);

124 copy(c, c+TIMES,
ostream_iterator<int>(cout," "));

125

126

127

128 exit(0);

129 }

130

LUA:

1
#!/usr/bin/env
lua

2

3 math.randomseed(os.time())

4

5 function randArr1(a,
n)

6 for i=1,n
do

7 while true do

8 local temp = math.random(1, n)

9

10 local j = 1

11 while j < i do

12 if a[j] == temp then

13 break

14 end

15 -- Again damed that There is no ++

16 -- and even no composite operator += !

17 -- No one knows that is more concision

18 -- and more effective?

19 j
= j + 1

20 end

21

22 if j == i then

23 a[i]
= temp

24 break

25 end

26

27 end

28 end

29 end

30

31

32 function randArr2(a,
n)

33 -- use nil as false as a lua's special hack

34 local bt = {}

35 for i=1,n
do

36 while true do

37 local temp = math.random(1,n)

38 if not bt[temp]
then

39 a[i]
= temp

40 bt[temp]
= true

41 break

42 end

43 end

44 end

45 end

46

47 function randArr3(a,
n)

48 for i=1,n
do

49 a[i]
= i

50 end

51

52 for i=1,n
do

53 local temp = math.random(1,n)

54 -- one of the most things i like in lua&py

55 a[i],a[temp]
= a[temp],a[i]

56 end

57 end

58

59

60

61 -- Test Code

62

63 times = 100

64 t = {}

65 randArr1(t, times)

66 for i,v in ipairs(t)
do

67 io.write(v .. "
")

68 end

69

70

71 t2 = {}

72 randArr2(t2, times)

73 for i,v in ipairs(t2)
do

74 io.write(v .. "
")

75 end

76

77

78 t3 = {}

79 randArr3(t3, times)

80 for i,v in ipairs(t3)
do

81 io.write(v .. "
")

82 end

83

84

85

PYTHON:

1
#!/usr/bin/env
python

2 from random
import randint

3

4 def randArr1(a,n):

5 for i in range(n):

6 while True:

7 temp
= randint(0, n-1)

8

9 for j in range(i):

10 if a[j] == temp:

11 break;

12 # another one of the things I like in py(for else)

13 else:

14 a.append(temp)

15 break;

16

17 def randArr2(a,n):

18 #surely it is
not need be a dict but dict is faster then list

19 bd = {}

20 for i in range(n):

21 while True:

22 temp
= randint(0, n-1)

23 if temp not in tl:

24 a.append(temp)

25 tl[temp]
= True

26 break

27

28 def randArr3(a,n):

29 a = range(n)

30 for i in range(n):

31
temp = randint(0, n-1)

32
# like in lua

33
a[i],a[temp] = a[temp],a[i]

34

35 def test():

36 times = 100

37 l = []

38 randArr1(l,
times)

39

40 print l

41 l2 = []

42 randArr1(l2,
times)

43 print l2

44

45 l2 = []

46 randArr1(l2,
times)

47 print l2

48

49

50

51 if __name__ == '__main__':

52 test()

BASH:

1
#!/usr/bin/env
bash

2

3

4 #
just for a range rand....let me die....

5 #
what I had said? bash is not a good

6 #
language for describing algorithms

7 randInt()

8 {

9 local a=$1

10 local b=$2

11

12 if (( a
> b ))

13 then

14 local temp

15 (( temp = a ))

16 (( a = b ))

17 (( b = temp ))

18 fi

19

20 local mi

21 (( mi = b
- a + 1))

22 local r=$((RANDOM%${mi}+${a}))

23 echo -n $r

24 }

25

26 randArr1()

27 {

28 # only one
argument because I hate the

29 # bash's
indirect reference

30 # you can
reference the (4) binarySearch to

31 # see what
I said

32 local n=$1

33 declare -a a

34 for (( i=1; i<=n; ++i ))

35 do

36 while true

37 do

38 temp=`randInt 1 $n`

39 j=1

40 while (( j<i ))

41 do

42 if (( a[j] == temp ))

43 then

44 break

45 fi

46 (( ++j ))

47 done

48 if (( j
== i ))

49 then

50 (( a[j] = temp ))

51 break

52 fi

53 done

54 done

55

56 echo ${a[*]}

57 }

58

59 randArr2()

60 {

61 local n=$1

62 declare -a a

63 # used for bool array

64 declare -a b

65 for (( i=1; i<=n; ++i ))

66 do

67 while true

68 do

69 local temp=`randInt 1 $n`

70 if [ -z ${b[temp]} ]

71 then

72 (( a[i] = temp ))

73 (( b[temp] = true ))

74 break

75 fi

76 done

77 done

78

79 echo ${a[*]}

80 }

81

82 randArr3()

83 {

84 local n=$1

85 for (( i=1; i<=n; ++i ))

86 do

87 (( a[i] = i
))

88 done

89 for (( i=1; i<=n; ++i ))

90 do

91 local temp=`randInt 1 $n`

92 (( t = a[i] ))

93 (( a[i] = a[temp] ))

94 (( a[temp] = t
))

95 done

96

97 echo ${a[*]}

98 }

99

100

101 # so slow that
I can't bear it run 100 times

102 randArr1 10

103 randArr2 10

104 randArr3 10

105







write by 九天雁翎(JTianLing) -- blog.csdn.net/vagrxie