171. Excel Sheet Column Number

Description

Given a string columnTitle that represents the column title as appears in an Excel sheet, return its corresponding column number.

For example:

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

 

Example 1:

Input: columnTitle = "A"
Output: 1

Example 2:

Input: columnTitle = "AB"
Output: 28

Example 3:

Input: columnTitle = "ZY"
Output: 701

 

Constraints:

  • 1 <= columnTitle.length <= 7
  • columnTitle consists only of uppercase English letters.
  • columnTitle is in the range ["A", "FXSHRXW"].

Solutions

Solution 1

Python Code
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class Solution:
    def titleToNumber(self, columnTitle: str) -> int:
        res = 0
        for c in columnTitle:
            res = res * 26 + (ord(c) - ord('A') + 1)
        return res

Java Code
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class Solution {
    public int titleToNumber(String columnTitle) {
        int res = 0;
        for (char c : columnTitle.toCharArray()) {
            res = res * 26 + (c - 'A' + 1);
        }
        return res;
    }
}

C++ Code
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class Solution {
public:
    int titleToNumber(string columnTitle) {
        int res = 0;
        for (char c : columnTitle) {
            res = res * 26 + (c - 'A' + 1);
        }
        return res;
    }
};

Go Code
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func titleToNumber(columnTitle string) int {
	res := 0
	for _, c := range columnTitle {
		res = res*26 + int(c-'A'+1)
	}
	return res
}

TypeScript Code
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function titleToNumber(columnTitle: string): number {
    let res: number = 0;
    for (let char of columnTitle) {
        res = res * 26 + char.charCodeAt(0) - 64;
    }
    return res;
}