solve 171.excel-sheet-column-number

Author: andavid

vscode/171.excel-sheet-column-number.java

@@ -0,0 +1,64 @@
+/*
+ * @lc app=leetcode id=171 lang=java
+ *
+ * [171] Excel Sheet Column Number
+ *
+ * https://leetcode.com/problems/excel-sheet-column-number/description/
+ *
+ * algorithms
+ * Easy (52.16%)
+ * Likes:    612
+ * Dislikes: 117
+ * Total Accepted:    236K
+ * Total Submissions: 452K
+ * Testcase Example:  '"A"'
+ *
+ * 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
+ *
+ */
+class Solution {
+  public int titleToNumber(String s) {
+    int factor = 1;
+    int number = 0;
+    for (int i = s.length() - 1; i >= 0; i--) {
+      number += factor * (s.charAt(i) - 'A' + 1);
+      factor *= 26;
+    }
+    return number;
+  }
+}
+