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DOS批处理 & 脚本技术（批处理室） » [Closed] Permutations and Combinations

Floor1　pusofalse	Posted 2008-06-29 05:35
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Just give a group of strings, such as a b c List all permutations of a b c, that is, the output is as follows a b c a c b b a c b c a c a b c b a I use the brute-force method, triple for loops can get such results, but the number of characters is not necessarily... Like this... Ask the expert... Hope to summarize an efficient and practical method... [ Last edited by pusofalse on 2008-12-28 at 03:32 ]

Floor2　pusofalse	Posted 2008-06-29 10:22
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Worked on it for a whole morning, and then found out there's a major BUG. It turns out that only when there are three characters can all combinations be arranged. If there are more or fewer, it goes wrong. It has to be 3. I'm asking all the experts, is there a good way? @echo off&setlocal enabledelayedexpansion del ts.txt>nul 2>nul set var=1 2 3 :1 if defined var5 set var=%var5% for %%a in (%var%) do ( set dx=%%a set/a mn+=1 set !mn!=%%a call :lp ) if defined had echo 完成&pause>nul&exit/b for /l %%a in (%mn% -1 1) do set "var5=!var5!!%%a! " set had=had goto 1 :lp set var1=!var:%dx%=! for %%a in (%var1%) do ( set "var3=!var3!%%a " ) >>ts.txt echo %var3%%dx% set "%var3%%dx%=abcd" set var3= [ Last edited by pusofalse on 2008-6-29 at 10:29 AM ]

Floor3　bat-zw	Posted 2008-06-29 11:04
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I don't know if this meets the requirements: @echo off&setlocal enabledelayedexpansion if exist temp.txt del /q temp.txt :begin set code=abcd&set str=&set n=4 :again set /a a=%random%%%%n% set a=!code:~%a%,1! set code=!code:%a%=! set str=%str%%a% set /a n-=1 if "%str:~3%" equ "" goto again if defined var for %%i in (%var%) do if "%%i" equ "%str%" goto begin echo %str%>>temp.txt set var=%var% %str% set /a m+=1 if %m% lss 24 goto begin sort temp.txt&del /q temp.txt pause>nul

Floor4　pusofalse	Posted 2008-06-29 11:07
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The code given by Senior ZW also has bugs... It can only arrange combinations of four characters. If there are more than a few, only the first four are retained... If there are fewer, an error of dividing by zero will occur... The randomly given string, the number of strings is unknown...

Floor5　bat-zw	Posted 2008-06-29 11:29
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Originally posted by pusofalse at 2008-6-29 11:07: There are also bugs in the code provided by前辈 ZW... It can only arrange combinations of four characters. If there are more than a few, it only keeps the first four... If there are fewer, there will be an error of dividing by zero... The number of randomly given strings is unknown... The indeterminate number of characters is indeed a big problem. The following code basically achieves it (I think it's quite complicated): @echo off&setlocal enabledelayedexpansion if exist temp.txt del /q temp.txt :enter cls&set /p codes=Please enter the character group (separate characters with spaces): if not defined codes goto enter for %%i in (%codes%) do set /a m+=1 set /a num=1,x=m,y=m-1 :lp set /a num=m set /a m-=1 if %m% neq 0 goto lp :begin set code=!codes: =!&set str=&set /a n=x :again set /a a=%random%%%%n% set a=!code:~%a%,1! set code=!code:%a%=! set str=%str%%a% set /a n-=1 if "!str:~%y%!" equ "" goto again if exist temp.txt for /f "delims=" %%i in (temp.txt) do if "%%i" equ "%str%" goto begin echo %str%>>temp.txt set /a m+=1 if %m% lss %num% goto begin cls&sort temp.txt&del /q temp.txt pause>nul [ Last edited by zw19750516 on 2008-6-29 at 12:04 PM* ]

Floor6　pusofalse	Posted 2008-06-29 11:35
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Thanks a lot! Learning~

Floor7　bat-zw	Posted 2008-06-29 11:37
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Originally posted by pusofalse at 2008-6-29 11:35: Thanks a lot! Learning~ Such a method will be terribly slow when the number of characters exceeds six! Still need to find other methods.

Floor8　pusofalse	Posted 2008-06-29 11:46
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Hmm, it's tried. It's okay for less than 6 digits... Also, there's another bug. When entering a string like "b e e n" with two identical characters in it, it will go wrong.

Floor9　HAT	Posted 2008-06-29 11:52
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When I studied "Algorithm Design" before, I wrote such a C code, which is a recursive algorithm. /This program runs successfully under TC2.0/ /Algorithm 5.7 PERMUTATIONS1/ #include<stdio.h> int P; void print(int P,int n) { int i; printf("\n"); for(i=1;i<=n;i++) printf("%d",P); sleep(1); } void perm1(int m,int n) { int j,t; if(m==n) print(P,n); else for(j=m;j<=n;j++) { t=P; P=P; P=t; perm1(m+1,n); t=P; P=P; P=t; } } main() { int j,n; clrscr(); window(35,1,46,1); textbackground(4); textcolor(128); clrscr(); printf("www.cndos.cn\n"); printf("Please input the value of n:"); scanf("%d",&n); for(j=1;j<=n;j++) P=j; perm1(1,n); printf("\nPress any key to end."); getch(); }

Floor10　bat-zw	Posted 2008-06-29 11:52
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Characters that are the same are easy to handle: Add in the batch processing "for %%i in (%codes%) do set a=#%%i#&set b=!b! !a!", and then make corresponding processing. The specific code I won't write. It's just that the efficiency of the high position seems to be unable to be solved with batch processing, because using the method of set var=%var% %str% in my second floor will be limited by the total number of characters. [ Last edited by zw19750516 on 2008-6-29 at 12:02 PM ]

Floor11　plp626	Posted 2008-06-29 13:37
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```@echo off&setlocal enabledelayedexpansion set s1=a b c for %%a in (!s1!) do (set s2=!s1:%%a=! for %%b in (!s2!) do (set s3=!s2:%%b=! for %%c in (!s3!) do (echo %%a%%b%%c ) ) ) pause The 6-digit code is similar to```

Floor12　bat-zw	Posted 2008-06-29 13:47
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Finally improved a little bit of efficiency, local test permuting six-digit numbers takes nearly 10 minutes: @echo off&setlocal enabledelayedexpansion if exist pl.txt del /q pl.txt :enter cls&set /p codes=Please enter three or more characters (characters should be different and please separate with spaces): if not defined codes goto enter for %%i in (%codes%) do set /a m+=1 if %m% lss 3 set m=0&goto enter cls&echo Arranging, please wait... set /a num1=1,x=m,y=m-1 :lp set /a num1*=m,m-=1 if %m% neq 0 goto lp set /a num2=num1/6+1,sz=1 :begin set code=%codes: =%&set str=&set n=%x% :again set /a a=%random%%%%n%,n-=1 set a=!code:~%a%,1! set str=%str%%a%&set code=!code:%a%=! if "!str:~%y%!" equ "" goto again for /l %%a in (1,1,%sz%) do ( for %%i in (!var%%a!) do ( if "%%i" equ "%str%" goto begin ) ) echo %str%>>temp.txt set var%sz%=!var%sz%! %str% set /a m+=1,z+=1 if %z% equ 6 set /a sz+=1,z=0 if %m% neq %num1% goto begin sort temp.txt>pl.txt&del /q temp.txt&start pl.txt

Floor13　plp626	Posted 2008-06-29 14:07
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7-bit takes 2.28 seconds timediff.bat can be found in the forum p function library (used to calculate the difference between two time points) @echo off&setlocal enabledelayedexpansion set s1=a b c e d f g set t=%time% for %%a in (!s1!)do (set s2=!s1:%%a=! for %%b in (!s2!)do (set s3=!s2:%%b=! for %%c in (!s3!)do (set s4=!s3:%%c=! for %%d in (!s4!)do (set s5=!s4:%%d=! for %%e in (!s5!)do (set s6=!s5:%%e=! for %%f in (!s6!)do (set s7=!s6:%%f=! for %%g in (!s7!)do (echo %%a%%b%%c%%d%%e%%f%%g ) ) ) ) ) ) ) call timediff.bat %t% %time% 0 pause

Floor14　bat-zw	Posted 2008-06-29 16:33
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Originally posted by plp626 at 2008-6-29 14:07: 7 characters took 2.28 seconds timediff.bat can be found in the forum's p function library (used to calculate the difference between two time points) @echo off&setlocal enabledelayedexpansion set s1=a b c e d f g set t=%time% f ... The method is good, it's fast, but please clarify the original poster's intention: "The number of characters is not fixed".

Floor15　slore	Posted 2008-06-29 17:19
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Generate an n-layer nested bat and call it =.= Bat seems to be able to achieve "recursion" using parameters... But I haven't practiced this... Brain cells...

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