[LeetCode]:171:Excel Sheet Column Number

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 -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28

分析：

核心就是26进制转10进制，从低到高按位计算

代码：

public class Solution {
public static int titleToNumber(String s) {
int intResult = 0;
char[]chars=s.toCharArray();
int n =0;
for(int i = chars.length; i>0;i--){
intResult = intResult + ((int)chars[i-1]-64)*caleOffset(n);
n++;
}
return intResult;
}

public static int caleOffset(int n) {
int intResult = 1;
for(int i = 0; i< n;i++){
intResult = intResult*26;
}
return intResult;
}
}

高手的代码：从高位到低位，进位乘以26

class Solution {
public:
int titleToNumber(string s) {
int ret = 0;
for(int i = 0; i < s.size(); i ++)
ret = ret*26 + (s[i]-'A'+1);
return ret;
}
};