c permutation and combination with frequency

I have 2 strings where I have saved fixed 20 characters and these are “A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T” and same 20 char in string 2. so I will get 400 combinations of 2 character sets like

Code:

  AA,AB,AC,AD,AE,AF,……………AT
  BA,BB,BC,BD,BE,BF,…………..BT
  CA,CB,CC,CD,CE,CF……………CT

Code:

  #include<stdio.h>
  #include<conio.h>
  #include<string.h>
   
   
   
  int main()
  {
              int count = 0;
              char sequence1[30] = "ACDEFGHILPNQYWRKMTSV";
              char sequence2[30] = "ACDEFGHILPNQYWRKMTSV";
              const char sequence3[30] = "AAGACDF";        /*sequence taken from user which will be of length 31*/
              printf(" %s %s \n ",sequence1,sequence2);
              for (int i=0; i<strlen(sequence1); i++)
              {
                          for(int j=0;j<strlen(sequence2);j++)
                          {
                                printf(" %c %c",sequence1[i],sequence2[j]);
                                      for(int k=0; k < strlen(sequence3)-1; k++)
                                      {
                                                  if(sequence3[k] == sequence1[i] && sequence3[k+1] == sequence2[j])
                                                  {
                                                              //cout<<"(equal)\t";
                                                              count++;
                                                  }
                                      }
                          }
              }
   
              printf("the number of matches are found %d ",count);
              getch();
   
  }

This way we will get 400 combinations (Which program I have created successfully) but then user will put the value till 31 characters witch will be treated as 3rd string for E.g. “ABCDDAAAB” now I have to check the frequency of user input in the sequence of 12,23,34,45,56,67,78,89 (2 CHAR SET) means AB,BC,CD,DD,DA,AA,AA,AB and need to show the frequency
of user input

OUTPUT:

AB=2
BC=1
CD=1
DD=1
DA=1
AA=2

 

1:

2:

How are the two (1 and 2) linked ??
The problem that you mentioned in 2 can be solved independently !