redis自己构建的一种名为简单动态字符串（simple dynamic string，SDS）的抽象类型。

Given two binary strings, return their sum (also a binary string).

Implement pow(x, n), which calculates x raised to the power n (xn).

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*'.

Write a program to solve a Sudoku puzzle by filling the empty cells.

Determine if a 9x9 Sudoku board is valid.

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).