CODEWITHSUNDEEP
java
Kimmm
Kimmm

Reputation: 107

Sum of odd integers

I need to complete a method which is passed an int(max) as a parameter and returns the sum of the odd integers from 1 to max (inclusive).

For example, sumOfOddIntegers(5) must return 9. i.e. 1 + 3 + 5 = 9

My attempt was this:

int sumOfOddIntegers(int max) {
  int sumOdd = 0; 
  int digit; 
  while (max >= 1) { 
    digit = max%10; 
    if (digit%2 == 1)
      sumOdd += digit; 
    max /= 10; 
  }

  return sumOdd;
}

But it does not work with some inputs such as 5, 9, etc. What do I need to change in my code?

Upvotes: 1

Views: 7577

Answers (6)

Ortomala Lokni
Ortomala Lokni

Reputation: 62466

To make the sum of odd integers from 1 to max, you can use the Java 8 Streams

  public static int sumOddIntegers(int max){
        if(max<1) return 0;
        return IntStream.rangeClosed(1, max).filter(i -> i%2 != 0).sum();
    }

The following method calls are used:

  • IntStream.rangeClosed(1, max) to generate a stream of int from 1 to max.

  • filter(i->i%2!=0) to keep only odd int

  • sum() to make the sum.

You then find the right values.

Upvotes: 0

chans
chans

Reputation: 497

If you are trying to get s sum of odd number, you are not required to do digit = max%10; or max/= 10;

See the comments in your code, let say max = 98

   /****FIRST RUN****/
   // digit = 98%10 = 8
   digit = max%10; 
   // 8 % 2 == 0
   if( digit % 2 == 1 ) 
     sumOdd += digit; 
   // max = 98/10 = 9
   max/= 10; 

   /****SECOND RUN****/
   // digit = 9%10 = 9
   digit = max%10; 
   // 9 % 2 == 1
   if( digit % 2 == 1 ) 
     // sumOdd = 1
     sumOdd += digit; 
   // max = 9/10 = 0
   max/= 10;

Your output is 1, which is not what you expect. Hence, in order to compute sum of odd number you can proceed via:

for(int i = 1; i <= max; i+= 2)
{
   oddSum += i; // assuming oddSum = 0, and max is > 0
}

Upvotes: 4

shashikant
shashikant

Reputation: 21

Might be this helps :

import java.util.*;

class oddsum {
    public static void main(String args[]) {
        int sumOdd = 0;
        int digit;

        System.out.println("Please Enter Number.");
        Scanner in = new Scanner(System.in);
        int i = Integer.parseInt(in.nextLine());

        int j;
        for(j =1; j<=i; j+=2) {
            sumOdd += j;
        }

        System.out.println(sumOdd);
    }
}

Upvotes: 0

MD Sayem Ahmed
MD Sayem Ahmed

Reputation: 29166

  1. Write a method that will take a number as input, and will check whether or not it's odd. If the number is odd, it may return true, otherwise it may return false (HINT: odd numbers aren't divisible by 2).

  2. From your current method, loop from 1 to max. Pass each number to this method to check if it's odd or not. If it is, add it to the sum.

Upvotes: 0

aymankoo
aymankoo

Reputation: 671

here is some code

void calculateOdd(int max) {
  int total = 0;
  for (int i=max; i>0; i--) {
    if ( (i % 2) != 0 ) total+=i;
 }
 }

or 

void calculateOdd(int max) {
  int total = 0;
  if ( (max % 2) == 0 ) max--;
  for (int i=max; i>0; i--) {
     total+=i;
     i--;
  }
  }

Upvotes: 0

Breavyn
Breavyn

Reputation: 2242

why not just do this the easy way. Find the number of odd numbers in the range from 1 to max and then square it. This might help you http://www.wikihow.com/Add-a-Sequence-of-Consecutive-Odd-Numbers

Upvotes: 10

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