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algorithm notes: leetcode#171 excel sheet column number

admin 11月 12, 2020 0

Problem

Solution

Analysis

Python implementation

class :
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        ans = 0
        for i in range(len(s)):
            ans += (ord(s[-i-1]) - ord('A') + 1) * (26 ** i)
        return ans

Java implementation

class  {
    public int titleToNumber(String s) {
        int ans = 0;
        for(int i = 0; i < s.length(); i++)
            ans += Math.pow(26, i) * (s.charAt(s.length()-1-i) - 'A' + 1);
        return ans;
    }
}

Time complexity

O(N).

Space complexity

O(1).

Links

171. Excel Sheet Column Number
(中文版) 算法笔记: 力扣#171 Excel表列序号