For Python3 Platform

Mathematics Logic - Using combinations. Here it is nc2 = n*(n-1)/2

def handshakes(n):
    return (n*(n-1))//2

t = int(input())
for i in range(t):
    n = int(input())
    
    result = handshakes(n)
    
    print(result)

Yes, the formula n * (n - 1) / 2 works perfectly for this. It’s just the classic combination logic (C(n, 2)). If anyone’s looking for a simple breakdown of similar problem-solving patterns, you can click here for a quick resource I found useful.

Code belove or above most likly will give an error.

Coz Test Case will force you to cast answer to int before return

BRO! Its just a simple Combination Formula for C(N, 2) = N! / 2( N - 2)! = N ( N -1 )/2

int handshakes(int n) {
    return n * (n - 1) / 2;
}

You nailed it, happy coding 😍

Java 15

    public static int handshake(int n) {
        if (n < 2) {
            return 0;
        }
        return (n * (n - 1)) / 2;
    }