Tasks Details
medium
1.
CountDiv
Compute number of integers divisible by k in range [a..b].
Task Score
100%
Correctness
100%
Performance
100%
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.
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 21
Time spent on task 3 minutes
Notes
not defined yet
Code: 17:52:20 UTC,
java,
autosave
Code: 17:53:00 UTC,
swift4,
autosave
import Foundation
import Glibc
// you can write to stdout for debugging purposes, e.g.
// print("this is a debug message")
public func solution(_ A : Int, _ B : Int, _ K : Int) -> Int {
if A == 0 { A = 1 }
if B == 0 { B = 1 }
if A % K != 0 {
return (B / K) - (A / K)
} else {
return (B / K) - (A / K) + 1
}
}
Code: 17:53:31 UTC,
swift4,
verify,
result: Failed
import Foundation
import Glibc
// you can write to stdout for debugging purposes, e.g.
// print("this is a debug message")
public func solution(_ A : Int, _ B : Int, _ K : Int) -> Int {
if A == 0 { A = 1 }
if B == 0 { B = 1 }
if A % K != 0 {
return (B / K) - (A / K)
} else {
return (B / K) - (A / K) + 1
}
}
Analysis
Compile error
solution.swift:8:19: error: cannot assign to value: 'A' is a 'let' constant
if A == 0 { A = 1 }
~ ^
solution.swift:9:19: error: cannot assign to value: 'B' is a 'let' constant
if B == 0 { B = 1 }
~ ^
Code: 17:53:45 UTC,
swift4,
verify,
result: Failed
import Foundation
import Glibc
// you can write to stdout for debugging purposes, e.g.
// print("this is a debug message")
public func solution(_ A : Int, _ B : Int, _ K : Int) -> Int {
if A == 0 { A = 1 }
if B == 0 { B = 1 }
if A % K != 0 {
return (B / K) - (A / K)
} else {
return (B / K) - (A / K) + 1
}
}
Analysis
Compile error
solution.swift:8:19: error: cannot assign to value: 'A' is a 'let' constant
if A == 0 { A = 1 }
~ ^
solution.swift:9:19: error: cannot assign to value: 'B' is a 'let' constant
if B == 0 { B = 1 }
~ ^
Code: 17:53:55 UTC,
swift4,
autosave
import Foundation
import Glibc
// you can write to stdout for debugging purposes, e.g.
// print("this is a debug message")
public func solution(_ A : Int, _ B : Int, _ K : Int) -> Int {
if A == 0 { A = 1 }
if B == 0 { B = 1 }
if A % K != 0 {
return (B / K) - (A / K)
} else {
return (B / K) - (A / K) + 1
}
}
Code: 17:53:57 UTC,
swift4,
verify,
result: Passed
import Foundation
import Glibc
// you can write to stdout for debugging purposes, e.g.
// print("this is a debug message")
public func solution(_ A : Int, _ B : Int, _ K : Int) -> Int {
var A = A, B = B
if A == 0 { A = 1 }
if B == 0 { B = 1 }
if A % K != 0 {
return (B / K) - (A / K)
} else {
return (B / K) - (A / K) + 1
}
}
Analysis
Code: 17:54:28 UTC,
swift4,
autosave
Code: 17:54:29 UTC,
swift4,
verify,
result: Passed
Analysis
Code: 17:54:39 UTC,
swift4,
verify,
result: Passed
Analysis
Code: 17:54:45 UTC,
swift4,
final,
score:
100
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(1)
expand all
Correctness tests
1.
0.012 s
OK
1.
0.012 s
OK
2.
0.012 s
OK
1.
0.012 s
OK
2.
0.012 s
OK
3.
0.012 s
OK
1.
0.012 s
OK
2.
0.012 s
OK
3.
0.012 s
OK
4.
0.012 s
OK
5.
0.012 s
OK
6.
0.012 s
OK
expand all
Performance tests
1.
0.012 s
OK
1.
0.012 s
OK
1.
0.012 s
OK
2.
0.012 s
OK
1.
0.012 s
OK
2.
0.012 s
OK
3.
0.012 s
OK
4.
0.012 s
OK