Main17.java

package JZOfferTuJi;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class Main17 {
    Map<Character, Integer> ori = new HashMap<>();
    Map<Character, Integer> cnt = new HashMap<>();
    public String minWindow(String s, String t) {
        int tLen = t.length();
        for (int i = 0; i < tLen; i++) {
            char c = t.charAt(i);
            ori.put(c, ori.getOrDefault(c, 0) + 1);
        }
        int l = 0, r = -1;
        int len = Integer.MAX_VALUE, ansL = -1, ansR = -1;
        int sLen = s.length();
        while (r < sLen) {
            r++;
            if(r < sLen && ori.containsKey(s.charAt(r))) {
                cnt.put(s.charAt(r), cnt.getOrDefault(s.charAt(r), 0) + 1);
            }
            while (check() && l <= r) {
                if(r - l + 1 < len) {
                    len = r - l + 1;
                    ansL = l;
                    ansR = l + len;
                }
                if(ori.containsKey(s.charAt(l))) {
                    cnt.put(s.charAt(l), cnt.getOrDefault(s.charAt(l), 0) - 1);
                }
                l++;
            }
        }
        return ansL == -1 ? "" : s.substring(ansL, ansR);
    }

    private boolean check() {
        Iterator iter = ori.entrySet().iterator();
        while (iter.hasNext()) {
            Map.Entry entry = (Map.Entry) iter.next();
            Character key = (Character) entry.getKey();
            Integer val = (Integer) entry.getValue();
            if (cnt.getOrDefault(key, 0) < val) {
                return false;
            }
        }
        return true;
    }
}

class Main17_1{
    public static String minWindow(String s, String t) {
        int[] nums = new int[100];
        for (int i = 0; i < t.length(); i++) {
            nums[t.charAt(i) - 'A'] ++;
        }
        int l = 0, r = -1;
        int minLen = Integer.MAX_VALUE, ansL = -1, ansR = -1;
        while (r < s.length()) {
            r++;
            if(r < s.length()) {
                nums[s.charAt(r) - 'A'] --;
            }
            while (check(nums) && l <= r) {
                if(r - l + 1 < minLen) {
                    minLen = r - l + 1;
                    ansL = l;
                    ansR = l + minLen;
                }
                nums[s.charAt(l) - 'A'] ++;
                l++;
            }
        }
        return ansL == -1 ? "" : s.substring(ansL, ansR);
    }

    private static boolean check(int[] nums){
        for (int num : nums) {
            if (num > 0) {
                return false;
            }
        }
        return true;
    }

    public static void main(String[] args) {
        minWindow("ab", "a");
    }
}