709. To Lower Case

Posted 2021-02-08 17bdw

Algorithm

to-lower-case

https://leetcode.com/problems/to-lower-case/

1）problem

Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase.

Example 1:
    Input: "Hello"
    Output: "hello"
Example 2:
    Input: "here"
    Output: "here"
Example 3:
    Input: "LOVELY"
    Output: "lovely"

2）answer

声明一个新的字符串变量，对传入的字符串的字符逐个读取，如果是大写字母就取小写与大写之间的差值，得到大写字符对应的小写字母ASCII码存进字符串中。处理完后返回结果。

3）solution

Cpp：

#include <stdio.h>
#include <string>
using std::string;


class Solution {
public:
    string toLowerCase(string str) {
        string re_val = "";
        for (char str_val : str)
        {
            if (str_val >='A'&& str_val <='Z')
            {
                // 取小写与大写之间的差值，得到字符对应的小写ASCII码对应是什么存进字符串中
                re_val += (str_val + ('a' - 'A'));
            }
            else
            {
                // 如果是小写就不处理
                re_val += str_val;
            }

        }
        return re_val;

    }
};

int main() 
{

    // 使用内容
    Solution nSolution;
    nSolution.toLowerCase("hello World?");
    return 0;
}

Python：

class Solution(object):
    def toLowerCase(self, str):
        """
        :type str: str
        :rtype: str
        """
        ret = ""
        for s in str:
            if s>='A' and s<='Z':
                ret += chr(ord(s)+(ord('a')- ord('A')))
            else:
                ret +=s
                
        return ret