Left Rotate Array by K Positions

Code

#include <stdio.h>

void rotate_left(int arr[], int n, int k) {
    // k > 0
    // every element gets moved
    // space: O(k)
    // [1 2 3 4 5]
    // [1 3 2 4 5]
    // [1 3 4 2 5]
    // [1 3 4 5 2]
    // [1 3 4 5 2]
    // start at index = k-1
    // swap until index == n -1
    // iterate with index -= 1
    // stop at index 0
    int i = k % n;
    int r = n;
    while (i > 0) {
        int j = i;
        int h = i - 1;
        while (j < r) {
            int temp = arr[j];
            arr[j] = arr[h];
            arr[h] = temp;
            h++;
            j++;
        }
        i--;
        r--;
    } 
}

int main() {
    int n, k;
    scanf("%d %d", &n, &k);

    int arr[100];

    // Read array elements
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    // Rotate the array
    rotate_left(arr, n, k);

    // Print the rotated array
    for (int i = 0; i < n; i++) {
        printf("%d", arr[i]);
        if(i < n-1){
        	printf(" ");
        }
    }

    return 0;
}

Solving Approach

 

 

 

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Input

5 2 1 2 3 4 5

Expected Output

3 4 5 1 2