From fe7dea1399313282c6721b1a391e646329b84eaf Mon Sep 17 00:00:00 2001
From: rituraj-abes <115390762+rituraj-abes@users.noreply.github.com>
Date: Sat, 14 Oct 2023 18:17:04 +0530
Subject: [PATCH] Create leetcode204.cpp

leetcode solution for question 204
---
 C++/leetcode204.cpp | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 C++/leetcode204.cpp

diff --git a/C++/leetcode204.cpp b/C++/leetcode204.cpp
new file mode 100644
index 00000000..2ffce8e3
--- /dev/null
+++ b/C++/leetcode204.cpp
@@ -0,0 +1,32 @@
+/*
+204. Count Primes
+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.
+*/
+class Solution {
+public:
+    int countPrimes(int n) {
+        if(n == 0)
+            return 0;
+        vector<bool> prime(n,true);
+        prime[0] = prime [1] = false ;
+        int ans = 0;
+        for(int i = 2 ; i<n ; i++)
+        {
+            if(prime[i])
+            {
+                ans++;
+                int j=2*i;
+                while(j<n)
+                {
+                    prime[j] = false;
+                    j = j + i ;
+                }
+            }
+        }
+        return ans;
+    }
+};