最长无重复子串

在 Leetcode 上看到一个题（原题地址），最长无重复子串。当时看的第一眼觉得或许可以用动态规划，今天空闲时间实现了一下。

题目

Given a string, find the length of the longest substring without repeating characters.

示例

Given "abcabcbb", the answer is "abc", which the length is 3.

Given "bbbbb", the answer is "b", with the length of 1.

Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

C++ 代码解法