Left Rotate Array by K Positions

Code

#include <stdio.h>

void reverse(int arr[], int start, int end) {
    while (start < end) {
        int temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}

void rotate_left(int arr[], int n, int k) {
    k = k % n;  // Handle cases where k > n
    reverse(arr, 0, k - 1);      // Reverse first k elements
    reverse(arr, k, n - 1);      // Reverse remaining elements
    reverse(arr, 0, n - 1);      // Reverse entire array
}

int main() {
    int n, k;
    scanf("%d %d", &n, &k);//5 2

    int arr[100];

    // Read array elements
    for (int i = 0; i < n; i++) {//0 1 2 3 4 
        scanf("%d", &arr[i]);//1 2 3 4 5
    }

    // 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

🔁 Left Rotate Array by K Positions (In-Place)

✅ Algorithm (Reverse Method)

1. Reverse the first k elements
2. Reverse the remaining n - k elements
3. Reverse the entire array