C PROGRAMMING PROGRAM • ARRAYS, SEARCHING & SORTING

Left-Rotate an Array by K Positions

Learn how to left-rotate an array by k positions using a clear C program.

IntermediateArraysModulusTemporary array

PROBLEM UNDERSTANDING

Input and expected output

Sample input

6
1 2 3 4 5 6
2

Sample output

3 4 5 6 1 2

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int size, values[100], rotated[100], positions;

    printf("Enter array size: ");
    scanf("%d", &size);
    if (size < 1 || size > 100) return 1;
    for (int index = 0; index < size; index++) scanf("%d", &values[index]);
    printf("Enter left-rotation count: ");
    scanf("%d", &positions);
    positions = ((positions % size) + size) % size;
    for (int index = 0; index < size; index++) rotated[index] = values[(index + positions) % size];
    for (int index = 0; index < size; index++) printf("%d%c", rotated[index], index == size - 1 ? '\n' : ' ');
    return 0;
}

CURRENT STEP

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EXPECTED OUTPUT FOR THE SAMPLE

3 4 5 6 1 2

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Map every output index to its source index using (index+K) modulo N.
Display the computed result.

Map every output index to its source index using (index+K) modulo N.

EFFICIENCY

Time and space complexity

Time complexity

O(n)

Auxiliary space

O(n)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.