15算法课程 171. Excel Sheet Column Number


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

Credits:

Special thanks to @ts for adding this problem and creating all test cases.

solution:

这个题其实要表达的意思就是要把一个26进制的数转化为一个十进制的数

所以按照10进制的那种算法，移位即乘以进率就行

code:

class Solution {
public:
int titleToNumber(string s) {
int t = 1;
int ans = 0;
for(int i = s.size() - 1; i >= 0; --i){
int n = s[i];
n -= 64;
ans += (n * t);
t *= 26;
}
return ans;
}
};