Merge pull request #9 from InnocentDaksh63/patch-1

Create 204_count_primes.java

Author: kishanrajput23

204_count_primes.java

@@ -0,0 +1,23 @@
+class Solution{
+public int countPrimes(int n) {
+    if(n <=1 ) return 0;
+    
+    boolean[] notPrime = new boolean[n];        
+    notPrime[0] = true; 
+    notPrime[1] = true; 
+
+    for(int i = 2; i < Math.sqrt(n); i++){
+        if(!notPrime[i]){
+            for(int j = 2; j*i < n; j++){
+                notPrime[i*j] = true; 
+            }
+        }
+    }
+    
+    int count = 0; 
+    for(int i = 2; i< notPrime.length; i++){
+        if(!notPrime[i]) count++;
+    }
+    return count; 
+}
+}