Question

Given an array of positive integers a, your task is to calculate the sum of every possible a[i] ∘a[j], where a[i]∘a[j] is the concatenation of the string representations of a[i] and a[j] respectively.

Example

• For a = [10, 2], the output should be concatenationsSum(a) = 1344.
  • a[0] ∘a[0] = 10 ∘10 = 1010,
  • a[0] ∘a[1] = 10 ∘2 = 102,
  • a[1] ∘a[0] = 2 ∘10 = 210,
  • a[1] ∘a[1] = 2 ∘2 = 22.

So the sum is equal to 1010 + 102 + 210 + 22 = 1344.

• For a = [8], the output should be concatenationsSum(a) = 88.

There is only one number in a, and a[0] ∘a[0] = 8 ∘8 = 88, so the answer is 88.

Input/Output

• [execution time limit] 3 seconds (java)
• [input] array.integer a

A non-empty array of positive integers.

Guaranteed constraints:
1 ≤ a.length ≤ 10⁵,
1 ≤ a[i] ≤ 10⁶.

• [output] integer64
  • The sum of all a[i] ∘a[j]s. It's guaranteed that the answer is less than 2⁵³.

[Java] Syntax Tips

Answer 1

The answer to the question is given below.

The java code is given below.

import java.util.Scanner; /* scanner package for user input */

public class concatenationsSum /* concatenationsSum class for calculations */
{
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter the number of elements in the array : ");
int n=sc.nextInt();   
System.out.println("Enter the elements of array: ");
int value;
int[] arr=new int[n]; /* array for storing n elements */
int sum=0; /* intializing sum as 0 */
for(int i=0;i<n;i++)
{
value=sc.nextInt();
arr[i]=value;
}
/* perfroming all concatenation's sum using two loops */
for(int i=0;i<n;i++)
{
String str1 = Integer.toString(arr[i]); /* converting integer to string by toString() function */
for(int j=0;j<n;j++)
{
String str2 = Integer.toString(arr[j]);
String str3=str1+str2;
int num=Integer.parseInt(str3); /* converting String to integer by parseInt() function */
sum=sum+num; /* adding every num to sum */
}
}
System.out.println("Total concatenationsum is : "+sum); /* printing the value of sum */
}
}



The screenshot of the running code is given below.





The screenshot of sample input and output is given below in the image.







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