LC#172 finds total trailing zeros in factorial of Number N, 2 aproaches

Author: NirmalSilwal

Leetcode/easy/FactorialTrailingZeroes172.java

@@ -0,0 +1,59 @@
+package easy;
+
+import java.math.BigInteger;
+
+public class FactorialTrailingZeroes172 {
+
+	public static int trailingZeroesNonOptimal(int n) {
+
+		BigInteger factN = factorial(n);
+
+		int count = 0;
+
+		while (factN.mod(BigInteger.TEN).equals(BigInteger.ZERO)) {
+			factN = factN.divide(BigInteger.valueOf(10));
+			count++;
+		}
+
+		return count;
+	}
+
+	// iterative approach to find factorial
+	private static BigInteger factorial(int n) {
+		if (n == 0 || n == 1)
+			return BigInteger.ONE;
+
+		BigInteger ans = BigInteger.ONE;
+
+		for (int i = 2; i <= n; i++) {
+			ans = ans.multiply(BigInteger.valueOf(i));
+		}
+
+		return ans;
+	}
+
+	// recursive approach to find factorial
+	private static BigInteger factorialRec(int n) {
+		if (n == 0 || n == 1)
+			return BigInteger.ONE;
+
+		return BigInteger.valueOf(n).multiply(factorialRec(n - 1));
+	}
+
+	// optimal code - accepted Oms solution
+	public static int trailingZeroes(int n) {
+
+		int count = 0;
+
+		while (n > 0) {
+			n = n / 5;
+			count = count + n;
+		}
+
+		return count;
+	}
+
+	public static void main(String[] args) {
+		System.out.println(trailingZeroes(10000));
+	}
+}