摘要：Determine whether an integer is a palindrome. Do this without extra space. 思想: 先计算出这个整数的逆序数，然后比较它和原来的数每位是否都相同即可。另外要注意负数没有回文数，还应该考虑overflow一定不是回文数。 AC代 阅读全文

摘要：Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below 阅读全文

摘要：Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 思想：一个整数的倒序，没啥说的，在long类型上比较来避免overflow。 AC代码： 1 class Soluti 阅读全文

摘要：The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font 阅读全文

摘要：Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters fo 阅读全文