Left Rotate Array by K Positions

Code

#include <stdio.h>

void reverse(int arr[], int left, int right){
    int temp = 0;
    int length = (right - left) + 1;
    for(int i =left;i<left + (length/2);i++){
        temp = arr[i];
        arr[i] = arr[right - (i-left)];
        arr[right - (i-left)] = temp;
    }
}

// void rotate_left(int arr[], int n, int k) {  // O(n*k) solution
//     // Your logic here
//     int i=0;
//     int temp =0;
//     while(i<k){
//         temp = arr[0];
//         for(int i=0;i<n-1;i++){
//             arr[i] = arr[i+1];
//         }
//         arr[n-1] = temp;
//         i++;
//     }
    
// }

void rotate_left(int arr[], int n, int k) { // O(n)
    k%=n;
    reverse(arr,0,k-1);
    reverse(arr,k,n-1);
    reverse(arr,0,n-1);
    
}

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