Add number of 0's in a factorial and update gitignore

Author: rp-code9

.gitignore

@@ -1,8 +1,12 @@
 # Compiled class file
 *.class
 
-# a.out
+# a.out/gcov
 *a.out
+*.cpp.gcov
+*.gcda
+*.gcno
+*.c.gcov
 
 # Log file
 *.log

README.md

@@ -197,6 +197,7 @@ Princeton Algorithms [Part 1](https://www.coursera.org/learn/algorithms-part1/)
     * Iterative [C++](problems/math/PascalTriangle.cpp)
 * Happy number [Wiki](https://en.wikipedia.org/wiki/Happy_number) [C++](problems/math/HappyNumber.cpp)
 * Excel Sheet Column Number [C++](problems/math/SheetColumnNumber.cpp)
+* Number of zeros in facorial [C++](problems/math/FactorialTrailingZeros.cpp)
 
 ## Permutation
 * Permutation of objects [Java](problems/queue/Permutation.java)

problems/math/FactorialTrailingZeros.cpp

@@ -0,0 +1,33 @@
+// number of trailing zeroes in n!
+// Leetcode https://leetcode.com/explore/interview/card/top-interview-questions-medium/113/math/816/
+
+#include <iostream>
+#include <climits>
+
+int trailingZeroes(const int n)
+{
+    int result = 0;
+    for (long i = 5; i <= n; i = i * 5) {
+        result = result + n / i;
+    }
+    return result;
+}
+
+void test(const int n)
+{
+    std::cout << "Number of trailing zeros in " << n << "! : " << trailingZeroes(n) << "\n";
+}
+
+int main()
+{
+    test(INT_MIN);
+    test(-1);
+    test(0);
+    test(1);
+    test(5);
+    test(10);
+    test(125);
+    test(200);
+    test(INT_MAX);
+    return 0;
+}