Array Reverse Using Java

In this article we are discuss about Basic Problem in Programming. How To Reverse a Array Elements.

Reverse a given array elements. For example1,

[1,2,3,4,5]

Output

[5,4,3,2,1]

example2,

Input

[3,5,1,2,4]

Output

[4,2,1,5,3]

1) With Extra Space (Copy Arrar) 

We can simple make a same size of array and copy from given array elements to new array variable.

Its takes o(n) Time Complexity. And more Space To Run Programme.

class arrayReverse{

public static void main(String[] args){

int[] arr={1,2,3,4,5};

int n=arr.length;

int[] brr=new int[n];

for(int i=0;i<n;i++){

brr[i]=arr[n-i-1];

}

for(int j=0;j<n;j++){

System.out.println(brr[j]);

}

}

}

2)With Out Extra Space.

We can Swap The Array Element One By One. Like First Element And Last. Second Element And Second Last Until Reach Middle Element.

class arrayReverseWithoutExtraSpace{

public static void main(String[] args){

int[] arr={1,2,3,4,5,6};

int n=arr.length;

int i=0;

int j=n-1;

while(i<j){

int temp=arr[i];

arr[i]=arr[j];

arr[j]=temp;

i+=1;

j-=1;

}

for(int k=0;k<n;k++){

System.out.println(arr[k]);

}

}

}