코딜리티 11

Write a function:

class Solution { public int solution(int A, int B, int K); }

that, given three integers A, B and K, returns the number of integers within the range [A..B] that are divisible by K, i.e.:

{ i : A ≤ i ≤ B, i mod K = 0 }

For example, for A = 6, B = 11 and K = 2, your function should return 3, because there are three numbers divisible by 2 within the range [6..11], namely 6, 8 and 10.

Write an efficient algorithm for the following assumptions:

A and B are integers within the range [0..2,000,000,000];
K is an integer within the range [1..2,000,000,000];
A ≤ B.

 

public static int solution(int A, int B, int K) {
    // write your code in Java SE 8
    int ret = 0;
    ret = (B - A) / K;
    int r_a = A / K;
    int r_b = B / K;
    if (A % K == 0) {
        r_a  = r_a - 1;
        ret = ret + 1;
    }
    ret = r_b - r_a;
    return ret;
}