New update is available. Click here to update.

Solve problems & track your progress

Checkout your overall progress in every topic here

Become

Sensei

in DSA topics

Open the topic and solve more problems associated with it to improve your skills

Check out the skill meter for every topic

See how many problems you are left with to solve for cracking any stage. Score more than zero to get your progress counted.

Problem

Submissions

Choose Students

Contributed by

Pankaj Sharma

Last Updated: 23 Feb, 2023

Medium

0/80

Avg time to solve 25 mins

Success Rate 75 %

5 upvotes

Problem Statement

You are the teacher of a class and you have N students in the class. You are asked to choose R students from your class for a competition. All your students are equally competent. Find the number of ways you can choose R students from a class of N students.

Note : Number of ways of choosing 0 students from N students is 1.

Detailed explanation ( Input/output format, Notes, Images )

Input format:

The first line of input contains an integer ‘T’ denoting the number of test cases.

Then the T test cases follow.

The first line of each test case contains two space separated integers ‘N’ and ‘R’ denoting the total number of students in the class and number of students to choose respectively.

Output format:

For each test case, the number of ways to choose R students out of N is printed.
The output of each test case is printed in a separate line.

Constraints :

1 <= T <= 10
1 <= N <= 200
0 <= R <= N
where ‘T’ is the number of test cases, ‘N’ is the total number of students in the class and ‘R’ is the number of students to choose.

Sample Input 1:

1
3 2

Sample Output 1:

Explanation of Sample Input 1:

Ways to choose 2 students from 3 : {1,2}, {1,3}, {2,3}.

Sample Input 2:

Sample Output 2:

4
1
1

Auto

Console