滑动窗口---最小覆盖子串、字母异位词、

给你一个字符串 S、一个字符串 T，请在字符串 S 里面找出：包含 T 所有字母的最小子串。

/*
* https://leetcode-cn.com/problems/minimum-window-substring/
*
* 给你一个字符串 S、一个字符串 T，请在字符串 S 里面找出：包含 T 所有字母的最小子串。
* */
import java.util.HashMap;

public class code076_MinimumWindowSubstring
{
    public String minWindow(String s, String t) {
        if (s.length() == 0 || t.length() == 0){
            return "";
        }
        int start = 0, minLen = Integer.MAX_VALUE;
        HashMap<Character, Integer> window = new HashMap<>();
        HashMap<Character, Integer> needs = new HashMap<>();
        int left = 0, right = 0;
        for (int i = 0; i < t.length(); i++)
        {
            needs.put(t.charAt(i), needs.getOrDefault(t.charAt(i), 0) + 1);
        }
        int match = 0;
        while (right < s.length()){
            char c = s.charAt(right);
            if(needs.containsKey(c)){
                window.put(c, window.getOrDefault(c, 0) + 1);
                if(needs.get(c).compareTo(window.get(c)) == 0){
                    match++;
                }
            }
            right++;

            while (match == needs.size()){
                if(right - left < minLen){
                    start = left;
                    minLen = right - left;
                    System.out.println(minLen);
                }
                char c1 = s.charAt(left);
                if(needs.containsKey(c1)){
                    int num = window.get(c1);
                    window.put(c1, num - 1);
                    // System.out.println(String.valueOf(right) + ";" + c1 + ";" + String.valueOf(window.get(c1)));
                    if(window.get(c1) < needs.get(c1))
                        match--;
                }
                left++;
            }
        }
        return minLen == Integer.MAX_VALUE ? "" : s.substring(start, start + minLen);
    }
    public static void main(String[] args){
        code076_MinimumWindowSubstring minimumWindowSubstring = new code076_MinimumWindowSubstring();
        System.out.println(minimumWindowSubstring.minWindow("EBBANCF", "ABC"));
        System.out.println(minimumWindowSubstring.minWindow("ADOBECODEBANC", "ABC"));
        System.out.println(minimumWindowSubstring.minWindow("a", "aa"));

    }
}

给定一个字符串 s 和一个非空字符串 p，找到 s 中所有是 p 的字母异位词的子串，返回这些子串的起始索引。

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class code438_FindAllAnagramsinaString
{
    public List<Integer> findAnagrams(String s, String p) {
        List<Integer> list = new ArrayList<>();
        if (s.length() == 0 || p.length() == 0){
            return list;
        }
        HashMap<Character, Integer> window = new HashMap<>();
        HashMap<Character, Integer> needs = new HashMap<>();
        int left = 0, right = 0;
        for (int i = 0; i < p.length(); i++)
        {
            needs.put(p.charAt(i), needs.getOrDefault(p.charAt(i), 0) + 1);
        }
        int match = 0;
        while (right < s.length()){
            char c = s.charAt(right);
            if(needs.containsKey(c)){
                window.put(c, window.getOrDefault(c, 0) + 1);
                if(needs.get(c).compareTo(window.get(c)) == 0){
                    match++;
                }
            }
            right++;

            while (match == needs.size()){
                if(right - left == p.length()){
                    list.add(left);
                }
                char c1 = s.charAt(left);
                if(needs.containsKey(c1)){
                    int num = window.get(c1);
                    window.put(c1, num - 1);
                    if(window.get(c1) < needs.get(c1))
                        match--;
                }
                left++;
            }
        }
        return list;
    }
}