709. To Lower Case ¶ Time: $O(n)$ Space: $O(1)$ C++JavaPython 1 2 3 4 5 6 7 8 9 10 11 12class Solution { public: string toLowerCase(string str) { const int diff = 'A' - 'a'; for (char& c : str) if (c >= 'A' && c <= 'Z') c -= diff; return str; } }; 1 2 3 4 5 6 7 8 9 10 11 12 13class Solution { public String toLowerCase(String str) { final int diff = 'A' - 'a'; char[] ans = str.toCharArray(); for (int i = 0; i < ans.length; ++i) if (ans[i] >= 'A' && ans[i] <= 'Z') ans[i] -= diff; return new String(ans); } } 1 2 3class Solution: def toLowerCase(self, str: str) -> str: return ''.join(chr(ord(c) + 32) if 'A' <= c <= 'Z' else c for c in str)