[LeetCode] Longest Substring Without Repeating Cha

graf 發(fā)布于2019-08-19 10:52 / 766人閱讀

Problem

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.

很奇怪我為什么沒(méi)寫(xiě)過(guò)這道題...

Solution

class Solution {
    public int lengthOfLongestSubstring(String s) {
        if (s == null || s.length() == 0) return 0;
        Map dict = new HashMap<>();
        int start = 0, res = 0;
        for (int i = 0; i < s.length(); i++) {
            Character ch = s.charAt(i);
            Integer pre = dict.get(ch);
            if (pre != null && pre >= start) {
                res = Math.max(res, i - start);
                start = pre + 1;
            }
            dict.put(ch, i);
        }
        return Math.max(s.length()-start, res);
    }
}

云服務(wù)器 GPU云服務(wù)器 Repeating Without Longest LeetCode

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