osigmao的专栏

public class Solution { public String longestPalindrome(String s) { if (s == null) return null; int max = 0; String maxSub = ""; for (int beg = 0; beg < s.length();

public class Solution { public String multiply(String num1, String num2) { if (num1 == null || num2 == null) { return null; } int len1 = num1.length(); int l

1, 考虑溢出 -》用long。 If the correct value is out of the range of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.2，