1、题目
Related to question Excel Sheet Column Title
Given a column title as appear in an Excel sheet, return its corresponding column number.
For example:
A -> 1B -> 2C -> 3...Z -> 26AA -> 27AB -> 28 Credits:
Special thanks to @ts for adding this problem and creating all test cases.
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2、分析
A -> 1*26^0AA -> 1*26^1 + 1*26^0AAA -> 1*26^2 + 1*26^1 + 1*26^0
3、代码实现
public class Solution {public int titleToNumber(String value) {if (value == null || value.length() == 0) return 0;int length = value.length();//A 65char[] chars = value.toCharArray();int result = 0;int pow = 0;//please here is i >= 0 not is i > 0for (int i = length - 1; i >= 0; i--) {int tmp = chars[i] - 'A' + 1;int temp1 = (int)Math.pow(26, pow);pow++;result += tmp * temp1;}return result; }
}
4、总结
注意每次写
for(int i = length - 1; i > 0 --i)
的时候要注意不是这样写的，需要写成这样
for(int i = length - 1; i >= 0 --i)
不要忘记有=号，切记，以后不要换这样的错误。
还有求^的函数要知道，不要忘记
Math.pow(26, pow)
