## Question

Given an integer `n`

, return *the number of prime numbers that are strictly less than* `n`

.

**Example 1:**

Input:n = 10Output:4Explanation:There are 4 prime numbers less than 10, they are 2, 3, 5, 7.

**Example 2:**

Input:n = 0Output:0

**Example 3:**

Input:n = 1Output:0

**Constraints:**

`0 <= n <= 5 * 10`

^{6}

## Python Solution

class Solution: def countPrimes(self, n: int) -> int: arr = [0]*n c=0 for i in range(2,int(n**0.5)+1): for j in range(i*i,n,i): arr[j]=1 for k in range(2,len(arr)): if arr[k]==0: c+=1 return (c)