When can an algorithm have square root(n) time complexity?

Question

Can someone give me example of an algorithm that has square root(n) time complexity. What does square root time complexity even mean?

Answer 1

Primality test

Solution in JavaScript

 

const isPrime = n => {
    for(let i = 2; i <= Math.sqrt(n); i++) {
        if(n % i === 0) return false;
    }
    return true;
};

Complexity

O(N^1/2) Because, for a given value of n, you only need to find if its divisible by numbers from 2 to its root.