[leetcode]Longest Substring Without Repeating Characters

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public class Solution { public int lengthOfLongestSubstring(String s) { if (s.length() == 0) return 0; int start = 0; int longest = 0; HashMap<Character, Integer> lookup = new HashMap<Character, Integer>(); for (int i = 0; i < s.length(); i++){ char cur = s.charAt(i); if (lookup.containsKey(cur) && lookup.get(cur) >= start){ start = lookup.get(cur)+1; } lookup.put(cur, i); longest = Math.max(longest, i-start+1); } return longest; } }