# Covid Run(Solution)-Codechef October Long Challenge Solution

**Question**

**Covid-**1919 is spreading fast! There are N cities, numbered from 0 to (N−1), arranged in a circular manner. City 0 is connected to city 1, 1 to 2, ……, city (N−2) to city (N−1), and city (N−1) to city 0.

The virus is currently at city X. Each day, it jumps from its current city, to the city K to its right, i.e., from city X to the city (X+K)%N. As the virus jumps, the cities in between don’t get infected. Cities once infected stay infected. You live in city Y. **Find if it will reach your city eventually.** If it will, print **YES**, else print **NO**.

# Input:

- The first line of the input consists of an integer T, the number of test cases.
- The first and only line of each test case contains four space-separated integers — N, K, X and Y, denoting the number of cities, the size of jumps, Covid’s current city, and the city that you live in, respectively.

# Output:

For each test case, in a new line, print **YES** if Covid shall reach your city after a finite number of days, else print **NO**.

# Constraints

- 1≤T≤1001≤T≤100
- 1≤N≤10001≤N≤1000
- 0≤X,Y≤N−10≤X,Y≤N−1
- 0≤K≤10000≤K≤1000

# Subtasks

- Subtask 1–100% — Original constraints

# Sample Input:

`2`

6 2 5 3

12 3 4 2

# Sample Output:

`YES`

NO

# Explanation:

- In the
**first sample**, Covid starts at city 55, then goes to city 11, and then from city 11 to city 33. Thus, it reaches the city that you live in. - In the
**second sample**, Covid starts at city 44, goes to city 77, then 1010, 11, then 44, 77, 1010, ……, and so on. It never reaches city 22.

**Solution**

import java.util.*;

import java.lang.*;

import java.io.*;class Codechef

{

public static void main (String[] args) throws java.lang.Exception

{

Scanner sc = new Scanner(System.in);

int t = sc.nextInt();

while(t-- > 0){

int n = sc.nextInt();

int k = sc.nextInt();

int x = sc.nextInt();

int y = sc.nextInt();

int j=0;

if(y>n){

System.out.println("NO");

}

else{

for(int i=1;i<=n;i++){

if((x+k*i)%n == y){

System.out.println("YES");

j--;

break;

}

}

}

if(j==0)

System.out.println("NO");

}

}

}

This solution is Just for the understanding of logic after the contest is over. In no way I urge you to cheat in the contest. Remember these challenges are only for learning.

Question Link: