lintcode:Longest Substring Without Repeating Characters

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

Example

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.

Challenge

O(n) time

class Solution {public:    /**     * @param s: a string     * @return: an integer      */    int lengthOfLongestSubstring(string s) {        // write your code here        vector<int> dp(s.size()+1);        map<int, int> posMap;                dp[0] = 0;        int retMax = 0;                for (int i=0; i<s.size(); i++)        {            if (posMap.count(s.at(i)) == 0)            {                dp[i+1] = dp[i]+1;            }            else            {                dp[i+1] = min(i-posMap[s.at(i)], dp[i]+1);            }                        posMap[s.at(i)] = i;                        retMax = max(retMax, dp[i+1]);        }                return retMax;    }};