Longest Substring Without Repeating Characters,求没有重复字符的最长字串
问题描述:
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.
算法分析:使用滑动窗口,设置两个指针,遍历字符串。
public class LongestSubstringWithoutRepeatingCharacters { public int lengthOfLongestSubstring(String s) { int n = s.length(); Set<Character> set = new HashSet<>(); int ans = 0, i = 0, j = 0;//窗口左右指针 while(i < n && j < n) { if(!set.contains(s.charAt(j))) { set.add(s.charAt(j++)); ans = Math.max(ans, j - i); } else//如果有重复元素,则窗口左指针向右移动,直到移动到重复元素的下一位 { set.remove(s.charAt(i++)); } } return ans; } }