solve #172

Author: aylei

Diff for: src/lib.rs

@@ -157,3 +157,5 @@ mod n0166_fraction_to_recurring_decimal;
 mod n0167_two_sum_ii_input_array_is_sorted;
 mod n0168_excel_sheet_column_title;
 mod n0169_majority_element;
+mod n0171_excel_sheet_column_number;
+mod n0172_factorial_trailing_zeroes;

Diff for: src/n0171_excel_sheet_column_number.rs

@@ -0,0 +1,60 @@
+/**
+ * [171] Excel Sheet Column Number
+ *
+ * Given a column title as appear in an Excel sheet, return its corresponding column number.
+ * 
+ * For example:
+ * 
+ * 
+ *     A -> 1
+ *     B -> 2
+ *     C -> 3
+ *     ...
+ *     Z -> 26
+ *     AA -> 27
+ *     AB -> 28 
+ *     ...
+ * 
+ * 
+ * Example 1:
+ * 
+ * 
+ * Input: "A"
+ * Output: 1
+ * 
+ * 
+ * Example 2:
+ * 
+ * 
+ * Input: "AB"
+ * Output: 28
+ * 
+ * 
+ * Example 3:
+ * 
+ * 
+ * Input: "ZY"
+ * Output: 701
+ * 
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+// TODO: boring
+impl Solution {
+    pub fn title_to_number(s: String) -> i32 {
+        0
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_171() {
+    }
+}

Diff for: src/n0172_factorial_trailing_zeroes.rs

@@ -0,0 +1,52 @@
+/**
+ * [172] Factorial Trailing Zeroes
+ *
+ * Given an integer n, return the number of trailing zeroes in n!.
+ * 
+ * Example 1:
+ * 
+ * 
+ * Input: 3
+ * Output: 0
+ * Explanation: 3! = 6, no trailing zero.
+ * 
+ * Example 2:
+ * 
+ * 
+ * Input: 5
+ * Output: 1
+ * Explanation: 5! = 120, one trailing zero.
+ * 
+ * Note: Your solution should be in logarithmic time complexity.
+ * 
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn trailing_zeroes(n: i32) -> i32 {
+        let mut five_count = 0;
+        let mut n = n;
+        while n > 0 {
+            n = n / 5;
+            five_count += n;
+        }
+        five_count
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_172() {
+        assert_eq!(Solution::trailing_zeroes(3), 0);
+        assert_eq!(Solution::trailing_zeroes(5), 1);
+        assert_eq!(Solution::trailing_zeroes(20), 4);
+        assert_eq!(Solution::trailing_zeroes(1808548329), 452137076);
+    }
+}