Merge pull request #44 from Ankur-Dwivedi22/day_8medium

chore: completed day 8 medium task author:Ankur-Dwivedi22

Medium/Day8/Solution.cpp

@@ -1 +1,55 @@
 // Write Your code Here
+#include <iostream>
+#include <cstring>
+#include <cmath>
+using namespace std;
+
+const int max_num = 1e7;
+int is_prime[max_num + 1];
+int prime_count[max_num + 1];
+// prime_count[i] stores the number of primes up to i
+
+int main() {
+    // Input the number of test cases
+	int test_cases;
+	cin >> test_cases;
+
+	// Initialize arrays
+	memset(is_prime, 0, sizeof(is_prime));
+	prime_count[1] = prime_count[0] = 0;
+
+	// Sieve of Eratosthenes algorithm to find primes
+	for (int x = 2; x <= max_num; x++) {
+	    prime_count[x] = prime_count[x - 1];
+	    if (!is_prime[x]) {
+	        // Mark multiples of x as not prime
+	        for (int cur = x * 2; cur <= max_num; cur += x) {
+	            is_prime[cur] = 1;
+	        }
+	        // Increment prime count for each prime found
+	        prime_count[x]++;
+	    }
+	}
+
+	// Process each test case
+	while (test_cases--) {
+	    // Input the value of n
+	    int n;
+	    cin >> n;
+
+	    // Initialize ans to 0
+	    int ans = 0;
+
+	    // Check if n/2 is greater than or equal to 2
+	    if (n / 2 >= 2) 
+	        ans++;
+
+	    // Calculate ans by subtracting prime count up to n/2 from prime count up to n
+	    ans += prime_count[n] - prime_count[n / 2];
+
+	    // Output the answer for the current test case
+	    cout << ans << endl;
+	}
+
+	return 0;
+}