力扣：无重复字符最长子串

一、问题描述

二、解决路线

  采用滑动窗口法解决问题，相比较暴力解法的优化点：

三、代码实现

package demo1;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class LengthOfLongestSubstringPlus {
	public int lengthOfLongestSubstring(String s) {
		int n = s.length();
		int max = 0;
        Map<Character, Integer> map = new HashMap<>(); 
        for (int j = 0, i = 0; j < n; j++) {
            if (map.containsKey(s.charAt(j))) {
                i = Math.max(map.get(s.charAt(j)), i);
            }
            max = Math.max(max, j - i + 1);
            map.put(s.charAt(j), j + 1);
        }
        return max;
	}
	
	public static void main(String[] args) {
		
	LengthOfLongestSubstringPlus l = new LengthOfLongestSubstringPlus();
	Scanner sc = new Scanner(System.in);
	int max = 0;
	String str;
	System.out.println("输入str");
    str = sc.nextLine();
    max = l.lengthOfLongestSubstring(str);
    System.out.println("max = " + max);
}
}