題目地址:
https://leetcode.com/problems/to-lower-case/
給定一個字符串,將其大寫字母全轉換爲小寫後返回。代碼如下:
public class Solution {
public String toLowerCase(String str) {
if (str == null || str.isEmpty()) {
return str;
}
char[] cs = str.toCharArray();
for (int i = 0; i < cs.length; i++) {
if ('A' <= cs[i] && cs[i] <= 'Z') {
cs[i] = (char) (cs[i] - 'A' + 'a');
}
}
return new String(cs);
}
}
時空複雜度。