N-th Prime

Problem

Return the n-th prime number with 1-indexed counting, so nth_prime(1) is 2 and nth_prime(10) is 29.

Test candidate integers in increasing order and count primes until reaching n, checking divisibility only up to the square root. Return -1 for n < 1.

Hint

A number is prime when no divisor up to its square root divides it evenly.

case 1

in: [1]

expected: 2

case 2

in: [2]

expected: 3

case 3

in: [6]

expected: 13

case 4

in: [10]

expected: 29

case 5

in: [100]

expected: 541

Starter codePython

def nth_prime(n):
    # Your code here
    pass

5 test cases · run your code against them in the editor