Problem

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

Solution

Time complexity: O(n)

Space complexity: O(1)

// Author: Huahua

// Running time: 0 ms

class Solution {

public:

string toLowerCase(string str) {

for (char &c : str)

if (c >= 'A' && c <= 'Z') c = c - 'A' + 'a';

return str;

}

};

// Author: Huahua, 1 ms

class Solution {

public String toLowerCase(String str) {

char[] s = str.toCharArray();

for (int i = 0; i < s.length; ++i)

if (s[i] >= 'A' && s[i] <= 'Z') s[i] = (char)(s[i] - 'A' + 'a');

return new String(s);

}

# Author: Huahua, 40 ms

class Solution:

def toLowerCase(self, str):

ans = ''

for c in str:

if c >= 'A' and c <= 'Z':

ans += chr(ord(c) + 32)

else:

ans += c

return ans

# Author: Huahua, 68 ms

class Solution:

def toLowerCase(self, str):

return ''.join(chr(ord(c) + 32) if c >= 'A' and c <= 'Z' else c for c in str)