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 16 minutes
Notes
not defined yet
Code: 12:55:12 UTC,
java,
autosave
Analysis
User test case 1:
[0, 0, 1]
Analysis
User test case 1:
[0, 0, 11]
Analysis
Compile error
Solution.java:5: error: ';' expected
System.out.println(B / K)
^
1 error
Analysis
User test case 1:
[0, 0, 11]
Analysis
Compile error
Solution.java:5: error: cannot find symbol
System.out.println(Math.fllor((double)B / K));
^
symbol: method fllor(double)
location: class Math
1 error
Analysis
User test case 1:
[0, 0, 11]
Code: 12:58:45 UTC,
java,
verify,
result: Failed
Analysis
Compile error
Solution.java:11: error: cannot find symbol
int ret = floor(b/K) - floor((a - 1)/K); // b? ? - a?? ???? ?
^
symbol: method floor(double)
location: class Solution
Solution.java:11: error: cannot find symbol
int ret = floor(b/K) - floor((a - 1)/K); // b? ? - a?? ???? ?
^
symbol: method floor(double)
location: class Solution
2 errors
Code: 12:58:55 UTC,
java,
verify,
result: Failed
import java.util.*;
class Solution {
public int solution(int A, int B, int K) {
// System.out.println(Math.floor((double )B / K));
// return (B / K) - (A - 1) / K;
double a = A;
double b = B;
int ret = Math.floor(b/K) - Math.floor((a - 1)/K); // b의 몫 - a보다 작은수의 몫
return ret;
}
}
Analysis
Compile error
Solution.java:11: error: incompatible types: possible lossy conversion from double to int
int ret = Math.floor(b/K) - Math.floor((a - 1)/K); // b? ? - a?? ???? ?
^
1 error
Analysis
User test case 1:
[0, 0, 11]
Analysis
User test case 1:
[0, 12, 2]
Analysis
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
Analysis
expand all
User tests
1.
0.004 s
OK
function result: 6
function result: 6
stdout:
6
1.
0.004 s
OK
function result: 0
function result: 0
stdout:
0
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
Analysis
Compile error
Solution.java:5: error: cannot find symbol
return r = (B / K) + 1;
^
symbol: variable r
location: class Solution
Solution.java:7: error: cannot find symbol
r -= (A - 1) / K - 1;
^
symbol: variable r
location: class Solution
Solution.java:10: error: cannot find symbol
return r;
^
symbol: variable r
location: class Solution
3 errors
Analysis
expand all
Example tests
1.
0.004 s
WRONG ANSWER,
got 5 expected 3
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
Analysis
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
Analysis
expand all
User tests
1.
0.004 s
OK
function result: 7
function result: 7
1.
0.004 s
OK
function result: 1
function result: 1
1.
0.004 s
OK
function result: 2000000001
function result: 2000000001
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
User test case 3:
[0, 2000000000, 1]
Analysis
expand all
User tests
1.
0.004 s
OK
function result: 7
function result: 7
1.
0.008 s
OK
function result: 1
function result: 1
1.
0.008 s
OK
function result: 2000000001
function result: 2000000001
1.
0.008 s
OK
function result: 20
function result: 20
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
User test case 3:
[0, 2000000000, 1]
User test case 4:
[11, 354, 17]
Analysis
expand all
User tests
1.
0.004 s
OK
function result: 7
function result: 7
1.
0.004 s
OK
function result: 1
function result: 1
1.
0.004 s
OK
function result: 2000000001
function result: 2000000001
1.
0.004 s
OK
function result: 20
function result: 20
1.
0.001 s
RUNTIME ERROR,
invalid input, integer value out of range: 12345678900
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
User test case 3:
[0, 2000000000, 1]
User test case 4:
[11, 354, 17]
User test case 5:
[101, 12345678900, 100000]
Analysis
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
User test case 3:
[0, 2000000000, 1]
User test case 4:
[11, 354, 17]
User test case 5:
[101, 1234567890, 100000]
Analysis
User test case 1:
[0, 12, 2]
User test case 2:
[0, 0, 11]
User test case 3:
[0, 2000000000, 1]
User test case 4:
[11, 354, 17]
User test case 5:
[101, 1234567890, 100000]
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(1)
expand all
Correctness tests
1.
0.004 s
OK
1.
0.008 s
OK
2.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
3.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
3.
0.004 s
OK
4.
0.004 s
OK
5.
0.004 s
OK
6.
0.004 s
OK
expand all
Performance tests
1.
0.004 s
OK
1.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
3.
0.004 s
OK
4.
0.004 s
OK