g0101_0200.s0171_excel_sheet_column_number.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0101_0200.s0171_excel_sheet_column_number;

// #Easy #Top_Interview_Questions #String #Math #2022_06_26_Time_2_ms_(76.43%)_Space_43_MB_(34.53%)

/**
 * 171 - Excel Sheet Column Number\.
 *
 * Easy
 *
 * Given a string `columnTitle` that represents the 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:** columnTitle = "A"
 *
 * **Output:** 1 
 *
 * **Example 2:**
 *
 * **Input:** columnTitle = "AB"
 *
 * **Output:** 28 
 *
 * **Example 3:**
 *
 * **Input:** columnTitle = "ZY"
 *
 * **Output:** 701 
 *
 * **Example 4:**
 *
 * **Input:** columnTitle = "FXSHRXW"
 *
 * **Output:** 2147483647 
 *
 * **Constraints:**
 *
 * *   `1 <= columnTitle.length <= 7`
 * *   `columnTitle` consists only of uppercase English letters.
 * *   `columnTitle` is in the range `["A", "FXSHRXW"]`.
**/
public class Solution {
    public int titleToNumber(String s) {
        int num = 0;
        int pow = 0;
        for (int i = s.length() - 1; i >= 0; i--) {
            num += (int) Math.pow(26, pow++) * (s.charAt(i) - 'A' + 1);
        }
        return num;
    }
}