HackerRank Fundamentals – Handshake

Challenge: Handshake

Subdomeniu: Fundamentals (fundamentals)

Scor cont: 10.0 / 10

Submission status: Accepted

Submission score: 1.0

Submission ID: 464742603

Limbaj: python3

Link challenge: https://www.hackerrank.com/challenges/handshake/problem

Cerinta

At the annual meeting of Board of Directors of Acme Inc.  If everyone attending shakes hands exactly one time with every other attendee, how many handshakes are there?

**Example**  
$n = 3$  

There are $3$ attendees, $p1$, $p2$ and $p3$.  $p1$ shakes hands with $p2$ and $p3$, and $p2$ shakes hands with $p3$.  Now they have all shaken hands after $3$ handshakes.  

**Function Description**  

Complete the *handshakes* function in the editor below.  

*handshakes* has the following parameter:  

- *int n:*  the number of attendees  

**Returns**  

- *int:*  the number of handshakes  

**Input Format**  
The first line contains the number of test cases $t$.  
Each of the following $t$ lines contains an integer, $n$.   

**Constraints**  

$1 \le t \le 1000$  
$0 \lt n \lt 10^6$  

**Sample Input**

    2
    1
    2

**Sample Output**  

    0
    1

**Explanation**

Case 1 : The lonely board member shakes no hands, hence 0.   
Case 2 : There are 2 board members, so 1 handshake takes place.

Cod sursa

#!/bin/python3
import sys
n=int(sys.stdin.readline())
for _ in range(n):
    x=int(sys.stdin.readline())
    print(x*(x-1)//2)