Soluție HackerRank pentru Dancing in Pairs, subdomeniul Number Theory, în Java 8. Include cerința formatată, exemple, explicația pașilor și cod sursă.
- Problemă: Dancing in Pairs
- Domeniu: Number Theory
- Limbaj: Java 8
Challenge: Dancing in Pairs
Subdomeniu: Number Theory (number-theory)
Scor cont: 40.0 / 40
Submission status: Accepted
Submission score: 1.0
Submission ID: 464729129
Limbaj: java8
Link challenge: https://www.hackerrank.com/challenges/dance-class/problem
Cerință
Bob is a dance teacher and he started dance classes recently. He observes a strange attendance pattern among his students. Initially, there are no students. On day *i*, a new student starts attending the class. The student stops attending the class, if and only if he has attended the class for i consecutive days.
Also, the student resumes attending the class, if and only if he has not attended the class for i consecutive days.
We denote the student who starts coming on day *i* as student *i*.
To mark attendance, `o` denotes present and `x` denotes absent.
For example, the schedule for student 1 from day 1 is as follows:
`oxoxoxoxoxoxoxoxoxox...`
The schedule for the student 3 from day 1 is as follows:
`xxoooxxxoooxxxoooxxx...`
(Student 3 starts attending the class from day 3, and stops attending from day 6, and then starts attending from day 9, and so on. )
The schedule for the student 5 from day 1 is as follows.
`xxxxoooooxxxxxoooooxxxxx...`
Bob wants his students to dance in pairs. However, if the number of students coming on day i is odd, then there will be someone who can't find a partner. So Bob wants to know if the number of students coming on day i is even or odd. We denote the number of students coming on day i as _N(i)_. Please find out whether _N(i)_ is even or odd.
Input format
The first line contains an integer, T, which denotes the number of test cases.
For each test case, there is an integer i
Output Format
For each test case, if _N(i)_ is even, then print `even`.
If _N(i)_ is odd, then print one line `odd`.
Constraints
1 ≤ *T* ≤ 100
1 ≤ *i* ≤ 10<sup>18</sup>
Sample Input
4
1
2
3
4
Sample Output
odd
odd
odd
even
Explanation
The number of students coming on day 1 is 1: only student #1 attends the class. So N(1)=1 and it is odd.
The number of students coming on day 2 is 1: student #2, so n(2)=1 and it is odd.
The number of students coming on day 3 is 3: student #1, student #2, and student #3. So N(3)=3 and it is odd.
The number of students coming on day 4 is 2: student #3 and student #4. So N(4)=2 and it is even.
Cod sursă
import java.util.Scanner;
public class Solution {
public static void main(final String[] args) {
try (final Scanner in = new Scanner(System.in)) {
for (int t = in.nextInt(); t > 0; t--) {
final long i = in.nextLong() + 1;
System.out.println(i == 2 || Math.ceil(Math.sqrt(i) - 1) % 2 == 1 ? "odd" : "even");
}
}
}
}