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Ganesh K S
Ganesh K S

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Left Rotate array by K elements using reverse approach

Given array

const arr=[1,2,3,4,5,6]
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Left Rotate array by 2 elements , Output will be ---

arr = [3,4,5,6,1,2]
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This problem can be solve with reverse array approach easily

  • First devide the array with given K elements to rotate
  • In our case K is 2

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  • Reverse the corresponding devision of elements
  • So after reversing the array will be

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  • Now reverse the whole array that will give you the output
  • After reversing whole array the output will be

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Implementation in Code level

let arr=[1,2,3,4,5,6]
let k=2

function reverseArray(arr,start,end){

    return arr;

//this will be the first step to reverse the first half
let reversedFirstHalf=reverseArray(arr,0,k-1)

//this will be the second step to reverse the second half
let reversedSecondHalf=reverseArray(reversedFirstHalf,k,arr.length-1)

//After reversing the whole array
let rotateArrayOutput = reverseArray(reversedSecondHalf,0,arr.length-1)
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