1. Reverse

1. Reverse the Array. 

Problem link :- Reverse the array
Algorithm idea :-

C code

//Reverse the array
#include<stdio.h>

void rev_arr(int arr[], int start, int end)
{
    int temp;

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


void print_arr(int arr[], int size)
{
    int i;

    for(i=0; i<size; i++)
        printf("\t%d",arr[i]);
    printf("\n");
}


void main()
{
    int arr1[30];
    int n, i;

    printf("Enter the size of the array\n");
    scanf("%d",&n);
    printf("Enter the elements of the array\n");
    for(i=0; i<n; i++)
        scanf("%d",&arr1[i]);

    printf("Array before reversing\n");
    print_arr(arr1, n);
    rev_arr(arr1, 0, n-1);
    printf("\nArray after reversing\n");
    print_arr(arr1, n);
}

Java code

//Reverse the array
package programs;

import java.util.*;

public class Array__1
{
	static void reverse(int arr[], int n)
	{
		int i, j, temp;
		i = 0;
		j = n-1;
		
		while(i<j)
		{
			temp = arr[i];
			arr[i] = arr[j];
			arr[j] = temp;
			i++;
			j--;
		}
	}
	
	static void print_array(int arr[], int n)
	{
		int i=0;
		for(i=0; i<n; i++)
			System.out.println(arr[i] + " ");
	}
	
	public static void main(String[] args)
	{
		int array[] = new int[30];
		int i, n;
		
		Scanner s = new Scanner(System.in);
		System.out .println("Enter the size of the array : ");
		n = s.nextInt();
		System.out.println("Enter the elements of the array\n");
		for(i=0; i<n; i++)
		{
			array[i] = s.nextInt();
		}
		
		System.out.println("Given array :\n");
		print_array(array, n);
		
		reverse(array, n);
		System.out.println("Array after reversing\n");
		print_array(array, n);
	}
}