C language to achieve mathematical composition and arrangement

Today want to use the C language to achieve the combination of mathematics and arrangement, has been very depressed.

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#include <stdio.h>

#include <stdlib.h>

From the array A of n elements, take the combination of M elements

BOOL Zuhe (char a[],int n,int m)

{The first X element that//p[x]=y takes is the y element of a

int index,i,*p;

p= (int*) malloc (sizeof (int) *m);

if (p==null)

{

return false;

}

index=0;

p[index]=0;//take the first element

while (true)

{

if (p[index]>=n)

{//Take the end, rewind

if (index==0)

{//All kinds of cases have been completed, can not be returned back

Break

}

index--;//back to the previous

p[index]++;//substitution Element

}

else if (index==m-1)

{//take enough, output

for (i=0;i<m;i++)

{

printf ("%c", A[p[i]);

}

printf ("\ n");

p[index]++; Replace element

}

Else

{//Take one more element

index++;

p[index]=p[index-1]+1;

}

}

Free (p);

return true;

}

Array A for n elements, all arranged

BOOL Pailie (char a[],int N)

{The first X element that//p[x]=y takes is the y element of a

int i,j,temp,*p;

p= (int*) malloc (sizeof (int) *n);

if (p==null)

{

return false;

}

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

{//initial arrangement

P[i]=i;

}

while (true)

{//Cycle m=n! times

Output a sort of arrangement

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

{

printf ("%c", A[p[i]);

}

printf ("\ n");

Look forward from the back to see if there are more than the number of the previous case, if there is a stop in the last number of positions.

For (i=n-1;i>0 && p[i]<p[i-1];i--);

If there is no more than the number of the previous number, the description has been to the last arrangement, return

if (i==0) break;

From the back to I, look for the smallest number greater than p[i-1], credited to J

For (J=n-1;j>i && p[j]<p[i-1];j--);

Exchange P[i-1] and P[j]

TEMP=P[I-1];p [i-1]=p[j];p [j]=temp;

Inverted p[i] to p[n-1]

for (i=i,j=n-1;i<j;i++,j--)