CareerCup

hmmm ok... homework?

for(int i=0; i+2<a.length; i+=3) swap(a[i], a[i+2]);

//Compiled code. Run it as it is.


public class ReverseArray {
	public int[] ReverseArrayInChunk(int[] arr){
		int temp;
		if(arr.length<3){
			return arr;
		}
		for(int i=0;i<arr.length;i=i+3){
			if(i+2<arr.length){
				temp=arr[i];
				arr[i]=arr[i+2];
				arr[i+2]=temp;
				
			}
		}
		
		return arr;	
		}
	public static void main(String[] args){
		int[] a= new int[]{1,2,3,4,5,6,7};
		ReverseArray ra=new ReverseArray();
		int[] b=ra.ReverseArrayInChunk(a);
		for(int j=0;j<b.length;j++){
			System.out.print(b[j]+", ");
		}
	}
}

Reverse3(int[] arr)
{
	int i =0;
	int j;
	int temp;
	while(arr.lenght > 0 && i < arr.length-2)
	{
		j= (i+2) > arr.lenght-1 ? i+1 : i+2;
		temp = arr[i];
		arr[i] = arr[j];
		arr[j] = temp'
		i =i+3;
	} 
}

Compiled Java code -

import java.util.Arrays;


public class SwapInThreeChunks {
	public static void main(String[] args)
	{
		int[] input = {1,9,6,4,5,8,3,1,5,2,4,5};
		
		for(int i=0, len=input.length; i<len; i++)
		{
			if(i+2 < len)
			{
				int temp = input[i];
				input[i] = input[i+2];
				input[i+2] = temp;
			}
			i += 2;
		}
		
		System.out.println(Arrays.toString(input));
	}
}

/**
* Reverse number in each chunk of k items in an array
*/
private static void reverseChunk(int[] raw, int k) {
if (k <= 1) return;
for(int i=0; i<raw.length; i=i+k) {
reverseChunk(raw, i, k);
}
}

private static void reverseChunk(int[] raw, int start, int k) {
if (start >= raw.length - 1) {
return;
}
int end = Math.min(raw.length - 1, start + k - 1);
if (end == start) {
return;
}
int j = start;
while (j < end + start - j) {
int tmp = raw[j];
raw[j] = raw[end + start -j];
raw[end + start - j] = tmp;
j++;
}
}

/**
* Reverse number in each chunk of k items in an array
*/
private static void reverseChunk(int[] raw, int k) {
if (k <= 1) return;
for(int i=0; i<raw.length; i=i+k) {
reverseChunk(raw, i, k);
}
}

private static void reverseChunk(int[] raw, int start, int k) {
if (start >= raw.length - 1) {
return;
}
int end = Math.min(raw.length - 1, start + k - 1);
if (end == start) {
return;
}
int j = start;
while (j < end + start - j) {
int tmp = raw[j];
raw[j] = raw[end + start -j];
raw[end + start - j] = tmp;
j++;
}
}

static int [] swapEle(int []A, int k){
		int i=0, l=A.length, j;
		while(i<l){
			
			j=i+k-1;
			if(j>=l){
				j=l-1;
			}
			while(i<j){
				swap(A, i, j);
				i++;
				j--;
			}
			if(k%2==0){
				i+=(k/2);
			} else i+=(k/2+1);
		}
		return A;
	}

void swap(int &a, int &b)
{
	int tmp=a;
	a=b;
	b=tmp;
}

void SwapInThrees(int *a, int n)
{
	int i;
	if(a==NULL || n<3)
		return;
	for(i=1;i<=n-2;)
	{
		swap(a[i+1],a[i-1]);
		i+=3;
	}

}

Here is working c++ code:

void reverse_chunks(int a[],int size, int chunk)
{
int index=0;
for(int i=0;i<size/chunk;index+=chunk,++i)
reverse_chunk(a,index,index+chunk-1);
if(index<size)
reverse_chunk(a,index,size-1);
}