LeetCode: Longest Substring Without Repeating Characters (3)

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.思路： 求最长不重复子字符串类问题， 可以将字符串按照顺序存放在连续的数组中即可。 在存入的时候判断是否重复，做香烟处理。遍历一次即可得到最长子串。时间复杂度：O（n）扩展：求最长重复子字符串#define max(x,y) (x>y)?(x):(y)
class Solution {
public:
int lengthOfLongestSubstring(string s) {
vector<int> hash(256,-1);
int sMax = 0;
int latestStart = 0;
int start =0;

for(int i= 0;i<s.length();i++)
{
//repeat char
if(hash[s[i]]!= -1)
{
sMax = max(sMax,i-start);
latestStart = start;
start = hash[s[i]]+1;
for(int j = latestStart;j<start;j++)
hash[s[j]] = -1;
}
hash[s[i]] = i;
}
return max(sMax,s.length()-start);
}
};