Created C program for 05.Smallest_multiple and CPP Program for 10.Summation_of_primes

C/05.Smallest_multiple/SanziSen.c

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+// C program to find smallest number evenly divisible by all numbers 1 to n 
+#include<stdio.h> 
+#include<stdlib.h>
+
+long long int gcd(long long int n1, long long int n2)
+{  long long int result,i;
+for(i=1; i <= n1 && i <= n2; ++i)
+    {
+        // Checks if i is factor of both integers
+        if(n1%i==0 && n2%i==0)
+            result = i;
+    }
+    return result;
+    }
+
+
+// Function returns the lcm of first n numbers 
+long long int lcm(long long n) 
+{ 
+    long long int ans = 1;     
+    for (long long int  i = 1; i <= n; i++) 
+        ans = (ans * i)/(gcd(ans, i)); 
+    return ans; 
+} 
+
+// Driver program to test the above function 
+int main()  
+{ 
+    long long n = 20; 
+    printf("%lld, lcm(n)); 
+    return 0; 
+} 

CPP/10.Summation_of_primes/SanziSen.cpp

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+
+#include<iostream> 
+#include<cstring>
+using namespace std; 
+
+long long int sumprimes(long long int n) 
+{ 
+
+    bool prime[n + 1]; 
+
+    // Create a boolean array "prime[0..n]" 
+    // and initialize all entries it as true. 
+    // A value in prime[i] will finally be 
+    // false if i is Not a prime, else true. 
+    memset(prime, true, n + 1); 
+
+    for (long long int p = 2; p * p <= n; p++) { 
+
+        // If prime[p] is not changed, then 
+        // it is a prime 
+        if (prime[p] == true) { 
+
+            // Update all multiples of p 
+            for (long long int i = p * 2; i <= n; i += p) 
+                prime[i] = false; 
+        } 
+    } 
+
+    // Return sum of primes generated through 
+    // Sieve. 
+   long long int sum = 0; 
+    for (long long int i = 2; i <= n; i++) 
+        if (prime[i]) 
+            sum += i; 
+    return sum; 
+} 
+
+// Driver code 
+int main() 
+{ 
+    int n = 2000000; 
+    cout << sumprimes(n); 
+    return 0; 
+}