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【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
思路: 实际上是做一个26进制的数字转换表,用一个数在for循环内纪录字符的位数，从而乘以基数26
public class Solution { public int titleToNumber(String s) { if(s==null||s.length()==0){ return 0; } int base = 0; for(int i = 0; i<s.length();i++){ base = base*26 + s.charAt(i)-‘A‘+1;//当有两位数的时候，base就是个位数*26 } return base; } }
逆问题：Excel Sheet Column Title【168】
Given a positive integer, return its corresponding column title as appear in an Excel sheet.
For example:
1 -> A
2 -> B
3 -> C
...
26 -> Z
27 -> AA
28 -> AB
思路：给n，用while循环，取出n的每一位，然后对应变换
public class Solution { public String convertToTitle(int n) { StringBuilder result = new StringBuilder(); while(n>0){ n--; result.insert(0, (char)(‘A‘ + n % 26)); n /= 26; } return result.toString(); } }
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原文地址：http://www.cnblogs.com/lucky-star-star/p/4960568.html
