CODEWITHSUNDEEP
calgorithm
Sergiy Shilingov
Sergiy Shilingov

Reputation: 125

Algorithm for searching unique elements combinations in C (elements position in resulting string doesn't matter)

I have code for char array unique elements searching. But it works incorrectly. For example, in case of "ABCD" array, I lose "ABD" case. How can I fix it?

#include <stdio.h>
#include <string.h>

void     fun(char *str, int size, int depth)
{
    int i = 0;
    int j = 0;
    int k = 0;
    while (i < size - depth + 1)
    {
        j = i + 1;
        while (j < size - depth + 2)
        {
            printf("%c", str[i]);
            k = j;
            while (k < j + depth - 1)
            {
                printf("%c", str[k]);
                k++;
            }
            printf("\n");
            j++;
        }
        i++;
    }
}

int     main(void)
{
    char    *str = "ABCD";
    int i = 0;
    while (i < strlen(str))
    {
        fun(str, strlen(str), i + 1);
        i++;
    }
    return (0);
}

The result is: A A A A B B B C C D AB AC AD BC BD CD ABC ACD BCD ABCD

And I need: A B C D AB AC AD BC BD CD ABC ABD ACD BCD ABCD

So as you can see there are several bugs - repeats of single chars at the beginning and missing ABD case. If the string is "ABCDE" there are more variants will be missing.

Upvotes: 2

Views: 512

Answers (1)

MrBlack
MrBlack

Reputation: 399

This code should fix the problem:

#include <string.h>
#include <stdio.h>

void fun(char *str, char *data, int start, int end, int idx, int depth)
{
    if (idx == depth)
    {
        for (int j = 0; j < depth; j++)
            printf("%c", data[j]);
        printf("\n");
        return;
    }
    for (int i = start; i <= end && end - i + 1 >= depth - idx; i++)
    {
        data[idx] = str[i];
        fun(str, data, i + 1, end, idx + 1, depth);
    }
}

int main()
{
    char *str = "ABCD";
    int i = 0;

    while (i < strlen(str))
    {
        char data[i + 1];
        fun(str, data, 0, strlen(str) - 1, 0, i + 1);
        i++;
    }
    return (0);
}

Output:

A B C D AB AC AD BC BD CD ABC ABD ACD BCD ABCD

And also works for "ABCDE" and etc.

Upvotes: 0

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