Lesson 3: CountDiv (Cound Div)

This is another simple math question.

See the figure above.

When A % K == 0, the answer can be given by (B - A) / K + 1.
When A % K != 0, the answer can be given by (B - (A - A % K)) / K.

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SOLUTION
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int solution(int A, int B, int K) 
{
    if (A % K == 0){
        return (B - A) / K + 1;
    }

    return (B - (A - A % K)) / K;
}