add ipi6

ws2019/ipi/uebungen/primfaktorzerlegung.cpp

@@ -0,0 +1,26 @@
+#include "cpp_headers/fcpp.hh"
+
+int main() {
+    int n = enter_int("Please enter a natural number: ");
+    // search smallest factor, start with smallest possible: 2
+    int k=2;
+    // go until sqrt(n)
+    while (k <= sqrt(n)) {
+        printf("searching for dividers for %d, checking %d\n", n, k);
+        // k is factor of n
+        if (n % k == 0) {
+            // print out the factor k
+            print(k);
+            // reset n to the quotient
+            n = n / k;
+            printf("found %d, setting n=%d\n", k, n);
+            // restart at k=2
+            k = 2;
+        } else {
+            // if k is not a factor, check next one
+            k++;
+        }
+    }
+    // n is the last prime factor of the original input number
+    print(n);
+}