LC761.特殊的二进制序列

• import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  
  /**
   * @author YAM
   */
  public class Test01 {
      public static void main(String[] args) {
          String s = "11011000";
          String ans = makeLargestSpecial(s);
          System.out.println("ans="+ans );
      }
  
  
      public static String makeLargestSpecial(String s) {
          if (s.length() <= 2) {
              return s;
          }
          int cnt = 0, left = 0;
          List<String> subs = new ArrayList<String>();
          for (int i = 0; i < s.length(); ++i) {
              if (s.charAt(i) == '1') {
                  ++cnt;
              } else {
                  --cnt;
                  if (cnt == 0) {
                      System.out.println("i="+i);
                      subs.add("1" + makeLargestSpecial(s.substring(left + 1, i)) + "0");
                      //递归如下：
                      // substring ( 1 , 7 ) , >= 1 && < 7
                      // makeLargestSpecial("101100")  first  s = "101100"为 非 特殊的二进制序列
                      // "101100" 拆解：@start
                      // substring ( 1 , 1 )  , >= 1 && < 1 , left = i(1) + 1 = 2
                      // makeLargestSpecial("")  second
                      // return s (空) subs.add("10") 第一次添加
                      // substring ( 3 , 5 )  , >=  3 && < 5
                      // makeLargestSpecial("10") third
                      // return s ("10") subs.add("1100") 第二次添加  @end
                      // subs = [10, 1100];
                      left = i + 1;
                      //i=7
                      //i=1
                      //i=5
                  }
              }
          }
          System.out.println("subs2="+subs);
          Collections.sort(subs, Comparator.reverseOrder());
          System.out.println("subs1="+subs);
          StringBuilder ans = new StringBuilder();
          for (String sub : subs) {
              ans.append(sub);
              System.out.println(sub);
          }
          return ans.toString();
      }
  
  
  }

以上注释即为递归解释