709. To Lower Case（python+cpp）

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题目：

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”

解释：
大写转小写
python代码：

class Solution(object):
    def toLowerCase(self, str):
        """
        :type str: str
        :rtype: str
        """
        return str.lower()    

python代码2：

class Solution(object):
    def toLowerCase(self, str):
        """
        :type str: str
        :rtype: str
        """
        result=[]
        SET="QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm"
        for s in str:
            if s in SET:
                if ord(s)<ord('a'):
                    result.append(chr(ord(s)+ord('a')-ord('A')))
                else:
                    result.append(s)
            else:
                result.append(s)
        return ''.join(result)

c++代码：

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
class Solution {
public:
    string toLowerCase(string str) {
        transform(str.begin(),str.end(),str.begin(),::tolower);
        return str;
    }
};

总结：
#include<algorithm>