Generate All Permutations of Array in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to swap two elements in the array.

DSA C

void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = [1];
}

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Aa

Btemp

Cb

D*temp

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning *a to *b instead of using temp.

Using incorrect pointer dereferencing.

The swap function uses a temporary variable to hold the value of *a before assigning *b to *a, then assigns temp to *b to complete the swap.

2fill in blank

medium

Complete the code to print the current permutation of the array.

DSA C

void printArray(int arr[], int size) {
    for (int i = 0; i < [1]; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

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A0

Barr

Ci

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using the array name instead of size in the loop condition.

Looping beyond the array bounds.

The loop should run from 0 to size-1 to print all elements of the array.

3fill in blank

hard

Fix the error in the recursive call to generate permutations.

DSA C

void permute(int arr[], int l, int r) {
    if (l == r) {
        printArray(arr, r + 1);
    } else {
        for (int i = l; i <= r; i++) {
            swap(&arr[l], &arr[i]);
            permute(arr, [1], r);
            swap(&arr[l], &arr[i]);
        }
    }
}

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Al + 1

Bi + 1

Cr + 1

Dl

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong index in the recursive call.

Not incrementing the left index causing infinite recursion.

The recursive call should move the left index forward by one to generate permutations of the remaining elements.

4fill in blank

hard

Fill both blanks to complete the for loop and swap calls correctly.

DSA C

for (int i = [1]; i <= [2]; i++) {
    swap(&arr[l], &arr[i]);
    permute(arr, l + 1, r);
    swap(&arr[l], &arr[i]);
}

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Al

Br

C0

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Starting loop from 0 instead of l.

Looping beyond r causing out-of-bounds errors.

The loop variable i starts at l and goes up to r to swap elements for generating permutations.

5fill in blank

hard

Fill all three blanks to complete the main function setup and call permutation.

DSA C

int main() {
    int arr[] = [1];
    int n = sizeof(arr) / sizeof(arr[0]);
    permute(arr, [2], [3]);
    return 0;
}

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A{1, 2, 3}

B0

Cn - 1

D{3, 2, 1}

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect array initialization.

Passing wrong indices to permute function.

The array is initialized with {1, 2, 3}, and permute is called with indices 0 and n-1 to cover the full array.