LeetCode/171.excel-sheet-column-number.cpp at master · AlienYou/LeetCode · GitHub

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/*
 * @lc app=leetcode id=171 lang=cpp
 *
 * [171] Excel Sheet Column Number
 *
 * https://leetcode.com/problems/excel-sheet-column-number/description/
 *
 * algorithms
 * Easy (56.70%)
 * Likes:    1544
 * Dislikes: 190
 * Total Accepted:    362K
 * Total Submissions: 636.5K
 * 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
 *
 *
 * Constraints:
 *
 *
 * 1 <= s.length <= 7
 * s consists only of uppercase English letters.
 * s is between "A" and "FXSHRXW".
 *
 *
 */

// @lc code=start
class Solution {
public:
     int titleToNumber(string s) {
        int ans = 0;
        for (int i = 0; i < s.length(); ++i) {
            ans += ans * 25 + (s[i] - 'A' + 1);
        }
        return ans;
    }
};
// @lc code=end