[Leetcode]61. Excel Sheet column number for Excel columns

Related to question Excel Sheet Column Title

Given a column title as appear in an Excel sheet, and return its corresponding column number.

For example:

    1,    B, 2    C-3    ...    27 AA, Z    

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

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Solution: Equivalent to 26 binary to 10 binary.

classSolution { Public:    intTitletonumber (strings) {intn = s.size (), res =0;  for(inti =0; I < n; ++i) Res+ = (ToUpper (s[i))-'A'+1) * (int) Pow ( -, N-i-1); returnRes; }};

Improvements that do not use the POW function:

classSolution { Public:    intTitletonumber (strings) {intn = s.size (), res =0, i =0;  for(; i < n-1; ++i) {//Note that you cannot loop to n-1 to prevent overflowRes + = (ToUpper (s[i))-'A'+1); Res*= -; }        returnRes + (ToUpper (s[i))-'A'+1); }};

[Leetcode]61. Excel Sheet column number for Excel columns