Create Combinations from Set {1,2,3,4,5} with 'C' Program

In summary, the conversation is about finding all possible combinations with three elements from a set of {1,2,3,4,5} and the request for a 'C' program to store and print these combinations. The suggested solution involves using three indexes and nested loops to generate the combinations.
  • #1
gradnu
21
0
I have a set {1,2,3,4,5} and I need all possible combinations with three elements. Example {1,2,3}, {1,2,4}, {1,2,5} etc.
Can somebody help me with a 'C' program that does this. I want to store {1,2,3} etc. in an array of size three and print out every time a new combination is formed.

Thanks,
gradnu
 
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  • #2
Assuming these are to be unique combinations, then an easy way to do this is 3 indexes:

Code:
    for(i = 0; i < 3; i++){
        for(j = i+1, j < 4; j++){
            (for k = j+1, k < 5; j++){
 
Last edited:
  • #3
You can do loops if they are not supposed to be unique as well.

for (first = 1; first < 5; first++)
for (second = 1; second < 5; second++)
for (third = 1; third < 5; third++)
printf("%d%d%d\n", first, second, third);

Which should print something like "111", "112", "113", "114", "115", "121", "122", "123", ...

k
 
  • #4
Thanks a lot guys.
 

1. How do you create combinations from a given set using a C program?

To create combinations from a given set using a C program, you can use a recursive function that generates all possible combinations by selecting elements from the set one at a time. This function can then be called repeatedly with different starting points to generate all possible combinations.

2. Can you explain the logic behind creating combinations from a given set in a C program?

To create combinations from a given set in a C program, you need to understand the concept of recursion. Recursion is a programming technique where a function calls itself until a specific condition is met. In this case, the function will keep generating combinations until all elements from the set have been selected.

3. How do you handle duplicate elements in a given set when creating combinations using a C program?

To handle duplicate elements in a given set when creating combinations using a C program, you can first remove the duplicates from the set before passing it to the recursive function. Alternatively, you can also use a data structure like a hash table to keep track of the elements that have already been selected to avoid generating duplicates.

4. Is it possible to create combinations from a set with a larger number of elements using a C program?

Yes, it is possible to create combinations from a set with a larger number of elements using a C program. However, as the number of elements increases, the number of combinations also increases exponentially, making it more resource-intensive and time-consuming to generate all combinations. Therefore, it is important to optimize the code and avoid unnecessary repetitions.

5. Can you provide an example of creating combinations from the set {1,2,3,4,5} using a C program?

Yes, for the given set {1,2,3,4,5}, the possible combinations are: {1,2},{1,3},{1,4},{1,5},{2,3},{2,4},{2,5},{3,4},{3,5},{4,5}. Here is a sample code in C that uses recursion to generate all possible combinations from the given set:

```c#include // Recursive function to generate combinationsvoid generateCombination(int arr[], int data[], int start, int end, int index, int r) { // Base case if (index == r) { // Print the combination for (int i = 0; i < r; i++) { printf("%d ", data[i]); } printf("\n"); return; } // Recursive call to select elements one at a time for (int i = start; i <= end && end - i + 1 >= r - index; i++) { data[index] = arr[i]; generateCombination(arr, data, i + 1, end, index + 1, r); }}int main() { int set[] = {1, 2, 3, 4, 5}; int r = 2; // Size of combinations int n = sizeof(set)/sizeof(set[0]); // Size of set int data[r]; // Temporary array to store combinations // Call the recursive function generateCombination(set, data, 0, n-1, 0, r); return 0;}```

This code will print all possible combinations of size 2 from the set {1,2,3,4,5} as shown below:

```1 21 31 41 52 32 42 53 43 54 5```

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