Sum of sub-array at 10:51

#1

how is the sum of sub-array with elements 4 and 5 zero?

#2

hello @wtakashish
see if we are getting same modulo in prefix sum i,e

…a . . . … … . . a …

then that means sum of elements between those two same modulo is divisible by n.
becuase then only
(a+something) %n = a%n
implies something%n=0

so let say we have
…a … a…a…a…
now here if i pick any two a then sum in between them will always be divisible by n.

so if p is the frequency of a in prefix sum array then p*(p-1)/2 such subarray will be there.

so there 4 is how many subarray are there with prefix sum %n equals to 4 . and then using above logic we are calculating total possible subarrays

#3

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#4

import java.util.*;
public class Main {
public static void main (String args[]) {

Scanner scn=new Scanner(System.in);
	
int val1=0,val2=0;


	int n=scn.nextInt();	
	int arr1[]=new int[n];
	int k=arr1.length-1;

	for (int i=0;i<arr1.length;i++)
	{
arr1[i]=scn.nextInt();

	int res=(int) ((arr1[i])*(Math.pow(10,k)));

//System.out.println(res);
k–;

	val1=val1+res;
	
	}

// System.out.println(val1);
//
int m=scn.nextInt();
int arr2[]=new int[m];
int l=arr2.length-1;
for (int i=0;i<arr2.length;i++)
{
arr2[i]=scn.nextInt();

int res=(int) ((arr2[i])*(Math.pow(10,l)));

		l--;
		
		val2=val2+res;
		
		}
	int fin=val1+val2;
	//System.out.print(fin);
	String num=String.valueOf(fin);		
	

	for (int i=0;i<num.length();i++)
		{
			System.out.print(num.charAt(i)+", ");}
			
		System.out.print("END");

}
}