• 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 
    ...
    AAA -> 703
    AAB -> 704
    

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

    分析

    用过Execl的都知道,上述字母是其列名称,数字代表第几列,本题是求给定一个A~Z组成的字符串序列,求出其在Execl表中的列数。
    由以上给出的示例可以看出规律,其中A~Z代表数字1~26,那么字符串怎么求呢?
    比如(由低到高逐位计算):

    A=1260=1
    A=2260=2
    ...
    AA=1260+1261=27
    AB=2260+1261=28
    ...
    AAA=1260+1261+1262=703
    AAB=2260+1261+1262=704

    AC代码

    class Solution {
    public:
        int titleToNumber(string s) {
            int len = strlen(s.c_str());
            if (len == 0)
                return 0;
    
            int count = 0 , p = 0;
            for (int i = len-1; i >= 0; i--)
            {
                count = count + Num(s[i]) * pow(26, p);
                p++;
            }
            return count;
        }
    
        int Num(char c)
        {
            switch (c)
            {
            case 'A':
                return 1; break;
            case 'B':
                return 2; break;
            case 'C':
                return 3; break;
            case 'D':
                return 4; break;
            case 'E':
                return 5; break;
            case 'F':
                return 6; break;
            case 'G':
                return 7; break;
            case 'H':
                return 8; break;
            case 'I':
                return 9; break;
            case 'J':
                return 10; break;
            case 'K':
                return 11; break;
            case 'L':
                return 12; break;
            case 'M':
                return 13; break;
            case 'N':
                return 14; break;
            case 'O':
                return 15; break;
            case 'P':
                return 16; break;
            case 'Q':
                return 17; break;
            case 'R':
                return 18; break;
            case 'S':
                return 19; break;
            case 'T':
                return 20; break;
            case 'U':
                return 21; break;
            case 'V':
                return 22; break;
            case 'W':
                return 23; break;
            case 'X':
                return 24; break;
            case 'Y':
                return 25; break;
            case 'Z':
                return 26; break;
            default:
                return 0;  break;
            }
        }
    };
    

    GitHub测试程序源码

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  • 原文地址:https://www.cnblogs.com/shine-yr/p/5214913.html
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