3.Longest Substring Without Repeating Characters

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本文详细解析了寻找字符串中最长无重复字符子串的算法实现，通过示例展示了如何利用滑动窗口和哈希映射（map）来高效解决问题。文章提供了完整的代码示例，并解释了其工作原理。

Given a string, find the length of the longest substringwithout repeating characters.

Example 1:

Input: "abcabcbb"
Output: 3 
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: "pwwkew"
Output: 3
Explanation: 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.

class Solution {
public:
int lengthOfLongestSubstring(string s) {
int result = 0;
int flag = -1;

map<char,int> smap;
for(int i = 0;i<s.size();i++)
{
if(smap.count(s[i]) && smap[s[i]] > flag)
{
flag = smap[s[i]];
}

smap[s[i]] = i;
result = max(result,i-flag);
}
return result;

}
};