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.
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思路：
维护一个HashMap存储每个字符的位置；两个指针i,j，维护最长子串的范围。
java code:
public class Solution {
public int lengthOfLongestSubstring(String s) {
if(s==null || s.length()==0) return 0;
Map<Character, Integer> map = new HashMap<Character, Integer>();
int max = 0;
for(int i=0,j=0;i<s.length();i++) {
char c = s.charAt(i);
if(map.containsKey(c)) {
j = Math.max(j, map.get(c)+1);
}
map.put(c, i);
max = Math.max(max, i-j+1);
}
return max;
}
}LeetCode:Longest Substring Without Repeating Characters
原文：http://blog.csdn.net/itismelzp/article/details/51540983