“レッスンは何曜日？”をJavaでやってみた。なんというか・・・Javaっぽい？

WhatDayIsMyLesson.java

package example;

import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;

import java.util.EnumMap;
import java.util.LinkedList;
import java.util.List;
import java.util.TreeSet;

import org.junit.Test;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

public class WhatDayIsMyLesson {

  public String execute(String input) {
    List<Applicant> applicants = ApplicantLoader.from(input);
    return LessonScheduler.arrange(applicants).toResultString();
  }

  public static class ApplicantLoader {

    public static List<Applicant> from(String input) {
      return new ApplicantLoader().applicantsOf(input);
    }

    private List<Applicant> applicantsOf(String input) {
      return FluentIterable.from(Splitter.on('|').split(input))
          .transform(new Function<String, Applicant>() {
            @Override
            public Applicant apply(String input) {
              return applicantOf(input);
            }
          }).toList();
    }

    private Applicant applicantOf(String input) {
      List<String> splits = Splitter.on('_').splitToList(input);
      int id = Integer.parseInt(splits.get(0));
      List<LessonDay> requestDays = requestDaysOf(splits.get(1));
      return new Applicant(id, requestDays);
    }

    private List<LessonDay> requestDaysOf(String input) {
      return FluentIterable.from(Lists.charactersOf(input))
          .transform(new Function<Character, LessonDay>() {
            @Override
            public LessonDay apply(Character input) {
              return LessonDay.of(input);
            }
          }).toList();
    }
  }

  public enum LessonDay {
    MONDAY('1'), TUESDAY('2'), WEDNESDAY('3'), THURSDAY('4'), FRIDAY('5');

    private final char value;

    private LessonDay(char value) {
      this.value = value;
    }

    public char getValue() {
      return value;
    }

    public static LessonDay of(char value) {
      for (LessonDay day : values()) {
        if (day.value == value) {
          return day;
        }
      }
      throw new IllegalArgumentException();
    }
  }

  public static class Applicant {

    private final int id;

    private final List<LessonDay> requestDays;

    private Applicant(int id, List<LessonDay> requestDays) {
      this.id = id;
      this.requestDays = ImmutableList.copyOf(requestDays);
    }

    public int getId() {
      return id;
    }

    public LessonDay getRequestDay(int index) {
      return requestDays.get(index);
    }
  }

  public static class LessonScheduler {

    private EnumMap<LessonDay, Lesson> lessons = new EnumMap<>(LessonDay.class);

    public static LessonScheduler arrange(List<Applicant> applicants) {
      LessonScheduler scheduler = new LessonScheduler();
      final LinkedList<Applicant> acceptedApplicants = new LinkedList<>();
      for (int i = 0; i < 5; i++) {
        for (Applicant applicant : applicants) {
          if (acceptedApplicants.contains(applicant)) {
            continue;
          }

          boolean accepted = scheduler.accept(applicant.getRequestDay(i),
              applicant);
          if (accepted) {
            acceptedApplicants.add(applicant);
          }
        }
      }
      return scheduler;
    }

    private boolean accept(LessonDay day, Applicant applicant) {
      return getLessonFor(day).accept(applicant);
    }

    private Lesson getLessonFor(LessonDay day) {
      if (!lessons.containsKey(day)) {
        lessons.put(day, new Lesson(day));
      }
      return lessons.get(day);
    }

    public String toResultString() {
      return Joiner.on('|').join(
          FluentIterable.from(lessons.values()).transform(
              new Function<Lesson, String>() {
                @Override
                public String apply(Lesson input) {
                  return input.toResultString();
                }
              }));
    }
  }

  public static class Lesson {

    private static final int CAPACITY = 4;

    private final LessonDay day;

    private TreeSet<Integer> acceptedApplicantIds = new TreeSet<>();

    public Lesson(LessonDay day) {
      this.day = day;
    }

    public boolean accept(Applicant applicant) {
      if (isFull()) {
        return false;
      }
      acceptedApplicantIds.add(applicant.getId());
      return true;
    }

    private boolean isFull() {
      return acceptedApplicantIds.size() >= CAPACITY;
    }

    public String toResultString() {
      return day.getValue() + "_" + Joiner.on(':').join(acceptedApplicantIds);
    }
  }

  @Test
  public void testAll() {
    /* 0 */test("1_12345", "1_1");
    /* 1 */test("30_32451", "3_30");
    /* 2 */test("1_12345|2_12345", "1_1:2");
    /* 3 */test("3_12345|2_12345|1_12345", "1_1:2:3");
    /* 4 */test("1_23415|2_12435|3_42135", "1_2|2_1|4_3");
    /* 5 */test("1_23415|2_12435|3_42135|4_31245|5_53124",
        "1_2|2_1|3_4|4_3|5_5");
    /* 6 */test("40_12345|21_12345|3_12345|61_12345|10_12345",
        "1_3:21:40:61|2_10");
    /* 7 */test(
        "1_23415|2_12435|3_42135|4_54321|5_12345|6_13524|7_42351|8_31254|9_24513|10_12345",
        "1_2:5:6:10|2_1:9|3_8|4_3:7|5_4");
    /* 8 */test(
        "1_54321|2_54321|3_54321|4_54321|5_54321|6_54321|7_54321|8_54321|9_54321|10_54321|11_54321|12_54321|13_54321|14_54321|15_54321|16_54321|17_54321|18_54321|19_54321|20_54321|21_54321",
        "1_17:18:19:20|2_13:14:15:16|3_9:10:11:12|4_5:6:7:8|5_1:2:3:4");
    /* 9 */test(
        "1_34152|2_23514|3_41325|4_15342|5_45312|6_35124|7_21453|8_52431|9_13245|10_54123|11_13245",
        "1_4:9:11|2_2:7|3_1:6|4_3:5|5_8:10");
    /* 10 */test(
        "92_41532|58_14325|40_25413|5_45132|71_35124|23_13452|60_35241|77_31542|53_13542|72_12354",
        "1_23:53:58:72|2_40|3_60:71:77|4_5:92");
    /* 11 */test(
        "55_24153|91_24531|9_12543|41_34215|72_15423|44_42531|6_42351|79_15243|21_35412|31_52413|74_24135|83_31254|33_35421|84_53421|89_53241|16_32415|36_15234|92_34521|62_12345|14_23415|40_23415|88_43251|52_45213|77_32154|59_53241",
        "1_9:36:72:79|2_14:55:74:91|3_21:33:41:83|4_6:44:52:88|5_31:59:84:89");
    /* 12 */test("62_52341|57_12543|6_52431", "1_57|5_6:62");
    /* 13 */test("71_52143|16_24531|7_14523|99_41532|37_54123|72_43251",
        "1_7|2_16|4_72:99|5_37:71");
    /* 14 */test(
        "29_23541|37_32145|28_34215|59_15234|27_35142|77_51324|23_31245|62_15342|46_23145|47_41523|7_52341|68_12534|5_43251",
        "1_59:62:68|2_29:46|3_23:27:28:37|4_5:47|5_7:77");
    /* 15 */test(
        "17_34152|89_23451|49_43152|61_32541|15_25413|63_34521|16_31452|8_41352|54_41532|42_34521|53_12453|88_34251|4_21453|93_34512|18_25134|67_25134|50_14523",
        "1_50:53|2_4:15:18:89|3_16:17:61:63|4_8:42:49:54|5_67:88:93");
    /* 16 */test(
        "10_23145|80_32154|41_41532|20_31254|96_45231|50_23514|28_12534|13_31425|52_12435|88_23541|69_34215|46_53241|22_24531|53_42351|84_15243|97_14352|8_24135|59_13524",
        "1_28:52:84:97|2_10:22:50:88|3_13:20:69:80|4_8:41:53:96|5_46:59");
    /* 17 */test(
        "90_21453|58_43521|69_42351|12_51432|34_14352|23_45321|77_35421|71_24531|95_24153|49_13254|9_45231|78_21534|15_43512|54_41532|52_54321|59_24513|57_41532|75_35214|24_12435|97_52341|39_12453|53_12435|48_51234|32_51234",
        "1_24:34:39:49|2_71:78:90:95|3_15:54:75:77|4_9:23:58:69|5_12:48:52:97");
    /* 18 */test(
        "99_42153|44_42351|88_14523|58_51234|82_14523|15_25134|74_25134|77_32145|60_13425|46_34512|45_12345|63_32145|98_15234|96_41325|38_43521|61_14325|26_21543|37_24153|40_31542|57_23415|97_12543|30_45231|56_41523|22_34512|83_31245|86_35412|16_54321",
        "1_45:60:82:88|2_15:26:37:74|3_40:46:63:77|4_38:44:96:99|5_16:30:58:98");
    /* 19 */test(
        "55_13524|64_41523|40_23451|99_25314|65_21453|69_31524|77_45231|62_51432|21_13542|81_13452|66_21534|33_41352|5_52314|90_31452|6_42135|93_42351|84_43125|54_45213|76_21453|19_52134|50_21435|61_13542|30_35421|43_25431|24_25341|31_15234|39_15243|20_51423|67_13524",
        "1_21:55:61:81|2_40:65:66:99|3_30:69:84:90|4_6:33:64:77|5_5:19:20:62");
  }

  void test(String input, String expected) {
    assertThat(execute(input), is(expected));
  }
}

• http://d.hatena.ne.jp/torazuka/20140509/yhpg
• http://d.hatena.ne.jp/torazuka/20140511/yhpg

うらろふの

• https://gist.github.com/backpaper0/a995ddf9783817de4560