摘要：
Given an encoded string, return it's decoded string.The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is be 阅读全文
摘要：
You have 4 cards each containing a number from 1 to 9. You need to judge whether they could operated through *, /, +, -, (, ) to get the value of 24. 阅读全文