2018-05-16

LeetCode

593 Valid Square

This is a pure math problem.

110 Balanced Binary Tree

I used recursion to solve this.

791 Custom Sort String

C# String Class

• to construct a string from char array: String s = new String(chars);
• to access character by index: char c0 = s[0]
• to convert a string to char array: s.ToCharArray()

415 Add Strings

• convert char to integer: (int) (c - '0')
• convert integer 0-9 to char: (char) ((int) '0' + i)

TODO 93 Restore IP Address

• IP Address format: 32-bits, 0 - 255 for each number.