codility 14번 CountDiv

CountDiv

 

 

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.

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class Solution {
    public int solution(int A, int B, int K) {
        // write your code in Java SE 8
        int cnt = 0;
        for(int i=A; i<=B; i++){
            if(i%K == 0){
                cnt++;
                cnt += (B - i) / K;
                break;
            }
        }
        return cnt;
    }
}

class Solution {
    public int solution(int A, int B, int K) {
        return B/K - A/K + (A%K == 0 ? 1: 0);
    }
}

 

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