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:
function solution(A, B, 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 JavaScript
Time spent on task 39 minutes
Notes
not defined yet
Code: 21:59:04 UTC,
java,
autosave
Code: 22:24:15 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const difference = B - A;
const estimate = Math.floor(difference / K);
if (A % K === 0 || B % K === 0) {
return estimate + 1;
}
if (B % K >= A % K) {
return estimate - 1;
}
return estimate;
}
Code: 22:24:16 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const difference = B - A;
const estimate = Math.floor(difference / K);
if (A % K === 0 || B % K === 0) {
return estimate + 1;
}
if (B % K >= A % K) {
return estimate - 1;
}
return estimate;
}
Analysis
Code: 22:36:59 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const nearestLow = Math.ceil(A / K) * K;
const nearestHigh = Math.floor(B / K) * K;
return (nearestHigh - nearestLow) / K + 1;
}
Code: 22:37:00 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const nearestLow = Math.ceil(A / K) * K;
const nearestHigh = Math.floor(B / K) * K;
return (nearestHigh - nearestLow) / K + 1;
}
Analysis
Code: 22:37:04 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const nearestLow = Math.ceil(A / K) * K;
const nearestHigh = Math.floor(B / K) * K;
return (nearestHigh - nearestLow) / K + 1;
}
Analysis
Code: 22:37:07 UTC,
js,
final,
score:
100
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A, B, K) {
// write your code in JavaScript (Node.js 8.9.4)
const nearestLow = Math.ceil(A / K) * K;
const nearestHigh = Math.floor(B / K) * K;
return (nearestHigh - nearestLow) / K + 1;
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(1)
expand all
Correctness tests
1.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
1.
0.072 s
OK
2.
0.068 s
OK
3.
0.068 s
OK
1.
0.068 s
OK
2.
0.068 s
OK
3.
0.072 s
OK
4.
0.072 s
OK
5.
0.072 s
OK
6.
0.068 s
OK
expand all
Performance tests
1.
0.068 s
OK
1.
0.068 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
3.
0.072 s
OK
4.
0.072 s
OK