# Count Primes LeetCode Programming Solutions | LeetCode Problem Solutions in C++, Java, & Python [💯Correct]

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Hello Programmers/Coders, Today we are going to share solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python. At Each Problem with Successful submission with all Test Cases Passed, you will get a score or marks and LeetCode Coins. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.

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In this post, you will find the solution for the Count Primes in C++, Java & Python-LeetCode problem. We are providing the correct and tested solutions to coding problems present on LeetCode. If you are not able to solve any problem, then you can take help from our Blog/website.

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LeetCode is one of the most well-known online judge platforms to help you enhance your skills, expand your knowledge and prepare for technical interviews.

LeetCode is for software engineers who are looking to practice technical questions and advance their skills. Mastering the questions in each level on LeetCode is a good way to prepare for technical interviews and keep your skills sharp. They also have a repository of solutions with the reasoning behind each step.

LeetCode has over 1,900 questions for you to practice, covering many different programming concepts. Every coding problem has a classification of either EasyMedium, or Hard.

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• Mathematics/Basic Logical Based Questions
• Arrays
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• Greedy Algorithms
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• Database
• Recursion, etc.

Leetcode has a huge number of test cases and questions from interviews too like Google, Amazon, Microsoft, Facebook, Adobe, Oracle, Linkedin, Goldman Sachs, etc. LeetCode helps you in getting a job in Top MNCs. To crack FAANG Companies, LeetCode problems can help you in building your logic.

Link for the ProblemCount Primes– LeetCode Problem

`Count Primes– LeetCode Problem`

### Problem:

Given an integer `n`, return the number of prime numbers that are strictly less than `n`.

Example 1:

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

Example 2:

```Input: n = 0
Output: 0
```

Example 3:

```Input: n = 1
Output: 0
```

Constraints:

• `0 <= n <= 5 * 106`
`Count Primes– LeetCode Solutions`
`Count Primes Solution in C++:`
```class Solution {
public:
int countPrimes(int n) {
if (n <= 2)
return false;

vector<bool> prime(n, true);
prime = false;
prime = false;

for (int i = 0; i < sqrt(n); ++i)
if (prime[i])
for (int j = i * i; j < n; j += i)
prime[j] = false;

return count(begin(prime), end(prime), true);
}
};
```
`Count Primes Solution in Java:`
```class Solution {
public int countPrimes(int n) {
if (n <= 2)
return 0;

int ans = 0;
boolean[] prime = new boolean[n];
Arrays.fill(prime, 2, n, true);

for (int i = 0; i < Math.sqrt(n); ++i)
if (prime[i])
for (int j = i * i; j < n; j += i)
prime[j] = false;

for (final boolean p : prime)
if (p)
++ans;

return ans;
}
}
```
`Count Primes Solution in Python:`
```class Solution:
def countPrimes(self, n: int) -> int:
if n <= 2:
return 0

isPrime = [False] * 2 + [True] * (n - 2)

for i in range(2, int(n**0.5) + 1):
if isPrime[i]:
for j in range(i * i, n, i):
isPrime[j] = False

return sum(isPrime)
```
• Time: O(nloglogn)
• Space: O(n) 