Leetcode: Longest Substring Without Repeating Characters (analysis & solution) (C++)

PROBLEM:
Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.
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Keys:
using two pointers to form a sliding window and scan from left to right. 

class Solution {

public:

       int lengthOfLongestSubstring(string s) {

              //check input

              if (s.size() <= 1)return s.size();

              map<char, int> mTmp;

              int left = 0, right = 0, len = s.size(), final = 0;

              //right processing

              while (right<len){

                     if (mTmp.find(s[right]) != mTmp.end()){

                           final = final>mTmp.size() ? final : mTmp.size();

                           //left processing

                           while (left <= right){

                                  if (s[left] != s[right]){

                                         mTmp.erase(s[left]);

                                         left++;

                                  }

                                  else{

                                         left++;

                        right++;

                                         break;

                                  }

                           }

                     }

                     else {

                           mTmp[s[right]] = right;

                           right++;

                     }

              }

              final = final>mTmp.size() ? final : mTmp.size();

              return final;

       }

};