Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.

Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid op...

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

speech是从python2系列就开始支持的，对应python3的版本没有适配好，存在一些兼容性的问题。

n对括号最多需要1+2+..+n次交换，当它是)))..(((的形式时，)))(((需要6次，然后把中间两个交换一下，))()((就还需要5次，再交换一次靠近左边的)(，变成了)())((就需要4次，而3次，只要2对括号。...

Avoid errors. Readability. Not everyone has the operator table memorized.