The implementation method of permutation and combination algorithm _c Language classic case _c language

Permutation and combinatorial algorithms are common algorithms for examining recursion, and these two algorithms can be implemented in a recursive and concise way.

After many groping and thinking, I summarize the following for reference.

The program code is as follows:

#include <stdio.h> #include <stdlib.h> char array[] = "ABCD";
#define N 4 #define M 3 int Queue[n] = {0};
int top = 0;
 
 int Flag[n] = {0};
 
   void Perm (int s, int n) {int i;
   if (s > N) {return;
     } if (s = = N) {for (i = 0; i < n; i++) {printf ("%c", Queue[i]);
     printf ("\ t");
   return;
       for (i = 0; i < n; i++) {if (flag[i] = = 0) {Flag[i] = 1;
       Queue[s] = Array[i];
       Perm (s+1, N);
     Flag[i] = 0;
 
   }} void Comb (int s, int n, int m) {int i;
 
   if (s > N) return;
     if (top = m) {for (i = 0; i < m; i++) {printf ("%c", Queue[i]);
     printf ("\ t");
   return;
   } queue[top++] = Array[s];
   Comb (s+1, n, m);
   top--;
 
 Comb (s+1, n, m);
   int main () {printf ("\nperm (): \ n");
   Perm (0, N);
   printf ("\ncombination (): \ n");
   Comb (0, N, M);
   printf ("\ n");
 return 0; }

Run Result:

Perm ():
abcd  abdc  acbd  acdb  adbc
adcb bacd badc Bcad BCDA  BDCA  cabd  cadb  cbad  cbda  cdab  cdba dabc dacb Dbac DBCA  dcab  DCBA
combination ():
ABC   abd   ACD   BCD

The above is a small set for everyone to bring the arrangement and the combination of algorithms to achieve the full range of _c Language classic cases, I hope to help you, a lot of support cloud Habitat Community ~