LeetCode *** 3. Longest Substring Without Repeating Characters

题目：

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

Examples:

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.

分析：

代码：

class Solution {
public:
int lengthOfLongestSubstring(string s) {
int start = 0,end, len = s.length(), res = INT_MIN;
vector<int> posRes(256, -1);
for (end = 0; end<len; ++end) {
if (posRes[s[end]] == -1)posRes[s[end]] = end;
else if(posRes[s[end]]>=start){
res = max(end - start, res);
start = posRes[s[end]] + 1;
posRes[s[end]] = end;
}
else posRes[s[end]] = end;
}
return max(end-start, res);
}
};