C Program to Find the Length of Longest Repeating Subsequence

This C Program finds the length of longest repeating sequence in a string.

Here is source code of the C Program to find the Length of the longest repeating sequence in a string. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C Program to Find the Length of the Longest Repeating Sequence in a String

```
 */ 
```
```
#include <stdio.h>
```
```
#include <string.h>
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```
char string[100], words[100][100];
```
```
int len = 0, word_cnt = 0;
```
```
int main()
```
```
{
```

    int i, j = 0, k, mlen = 0, rlen = 0, s = 0, c = 0, m = 0;

```
    printf("\nEnter the string:");
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```
    scanf(" %[^\n]s", string);
```

    for (len = 0;string[len] != '\0';len++);

```
    /* 
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     * Storing the individual words in an array

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     */
```
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    for (k = 0;k < len;k++)
```
```
    {
```
```
        if (string[k] != ' ')
```
```
        {
```
```
           words[s][j] = string[k];
```
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            j++;
```
```
        }
```
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        if (string[k] == ' ')
```
```
        {
```
```
            words[s][j] = '\0';
```
```
            j = 0;
```
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            s++;
```
```
            word_cnt++;
```
```
        }
```
```
    }
```
```
    word_cnt++;
```
```
    /* 
```

     * Compare on Word basis if same word is repeated then check next word & so on

     * Increment a counter when consecutive words are repeated

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     */
```
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    for (i = 0;i <= word_cnt;i++)
```
```
    {
```
```
        len = 0;
```

        for (j = i+1;j <= word_cnt-1;j++)

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        {
```

            if (strcmp(words[i], words[j]) != 0)

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            {
```
```
                continue;
```
```
            }
```

            else if (strcmp(words[i], words[j]) == 0)

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            {
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                len++;
```

                for (k = i+1, m = j+1;k < j;k++, m++)

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                {
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                    if (strcmp(words[k], words[m]) == 0)

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                    {
```
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                        len++;
```
```
                        continue;
```
```
                    }
```
```
                    else    
```
```
                    {    
```
```
                        break;
```
```
                    }
```
```
                }
```
```
                if (rlen < len)
```
```
                {
```
```
                    rlen = len;
```
```
                    len = 0;
```
```
                }
```
```
                len = 0;
```
```
            }
```
```
            /*
```

             * Finding length of Longest Repeated Sequence

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             */
```
```
            if (mlen < rlen)
```
```
            {
```
```
                s = i;
```
```
                mlen = rlen;
```
```
            }
```
```
        }
```
```
    }
```

    printf("\nLength of Longest Repeating Sequence:%d\n", mlen);

    printf ("\nTotal number of words : %d", mlen);

    printf ("\n The subsequence is : ");

    for (i = s, j = 0;j < mlen;i++, j++)

```
    printf(" %s", words[i]);
```
```
    char subseq[100];
```
```
    // concat all the words
```

    for (i = s, j = 0; j < mlen; i++, j++)

```
      strcat (subseq, words[i]);
```

    printf ("\nThe length of longest common subsequence is: %d", strlen(subseq)+1);

```
    printf("\n");
```
```
}
```

Enter the string:
Welcome to C Programming Class, Welcome Again to C Programming Class!
 
Length of Longest Repeating Sequence:3
 
Total number of words : 3
 The subsequence is :  to C Programming
The length of longest common subsequence is : 19

Sanfoundry Global Education & Learning Series – 1000 C Programs.

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