Leetcode 2894. Divisible and Non-divisible Sums Difference

 

Problem Statement:

 leetcode problem 2894. Divisible and Non-divisible Sums Difference - 

You are given positive integers n and m.

Define two integers as follows:num1: The sum of all integers in the range [1, n] (both inclusive) that are not divisible by m.
num2: The sum of all integers in the range [1, n] (both inclusive) that are divisible by m.

Return the integer num1 - num2.

Initial Code

class Solution {
    public int differenceOfSums(int n, int m) {
        int suma = 0;sumb=0; // ERROR: sumb not declared properly
        for (int i=1; i==n; i++){ // ERROR: i==n (this never iterates)
            if(i%m==0){
                sumb+=i;
            }else{
                suma+=i;
            }
        }
        return suma-sumb;
    }
}

Issues in the code:

• Variable declaration: sumb is undeclared.
• Loop condition: for (int i = 1; i == n; i++) executes only when i equals n, so it never loops. It must be i <= n.
• Minor style: combining declarations on one line makes it harder to read

Corrected code

class Solution {
    public int differenceOfSums(int n, int m) {
        int suma = 0;
        int sumb = 0;
        for (int i = 1; i <= n; i++) {
            if (i % m == 0) sumb += i;
            else suma += i;
        }
        return suma - sumb;
    }
}