ARTS

ARTS-04

Algorithm

无重复字符的最长子串(3)

解法1:

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import java.util.HashSet;
import java.util.Set;

/*
 * @lc app=leetcode.cn id=3 lang=java
 *
 * [3] 无重复字符的最长子串
 */
class Solution {
    public int lengthOfLongestSubstring(String s) {
        int result = 0;
        int l = s.length();
        for (int i = 0; i < l; i++) {
            for (int j = i + 1; j <= l; j++) {
                if (allUnique(s, i, j)) {
                    result = Math.max(result, j - i);
                }
            }
        }
        return result;
    }

    private boolean allUnique(String s, int start, int end) {
        Set<Character> set = new HashSet<>();
        for (int i = start; i < end; i++) {
            Character c = s.charAt(i);
            if (!set.contains(c)) {
                set.add(c);
            } else {
                return false;
            }
        }
        return true;
    }
}

暴力破解法没啥好说的, 直接超时了, 显然是不可行的.
时间复杂度：O(n^3)

解法2:

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