第9回オフラインリアルタイムどう書く（Java解答）

Busfee.java

package yhpg9;

import static org.junit.Assert.assertEquals;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.junit.Test;

/**
 * 問題: http://nabetani.sakura.ne.jp/hena/ord9busfare/
 */
public class Busfee {
  private final boolean isAdult(final String string) {
		return string.charAt(0) == 'A';
	}

	private final boolean isInfant(final String string) {
		return string.charAt(0) == 'I';
	}

	private final boolean hasPass(final String string) {
		return string.charAt(1) == 'p';
	}

	private final boolean hasWelfare(final String string) {
		return string.charAt(1) == 'w';
	}

	public String solve(final String input) {
		int base = Integer.valueOf(input.split(":")[0]);
		String passenger = input.split(":")[1];
		List<String> passengers = Arrays.asList(passenger.split(","));

		int adultNum = countAdult(passengers);
		int result = 0;

		int freeNum = 0;
		List<String> welfareInfants = new ArrayList<>();
		for (int i = 0; i < passengers.size(); i++) {
			String one = passengers.get(i);
			if (isInfant(one) && freeNum < adultNum * 2) {
				if (hasPass(one)) {
					continue;
				}
				if (hasWelfare(one)) {
					welfareInfants.add(one);
					continue;
				}
				freeNum++;
				continue;
			}
			result += getFee(one, base);
		}

		for (String each : welfareInfants) {
			if (freeNum < adultNum * 2) {
				freeNum++;
				continue;
			}
			result += getFee(each, base);
		}
		return String.valueOf(result);
	}

	private int getFee(final String target, final int base) {
		int tmp = 0;
		if (isAdult(target)) {
			tmp = base;
		} else {
			tmp = getHalf(base);
		}
		return discount(target, tmp);
	}

	private int discount(final String target, final int original) {
		if (hasPass(target)) {
			return 0;
		} else if (hasWelfare(target)) {
			return getHalf(original);
		}
		return original;
	}

	private int getHalf(final int n) {
		int tmp = n / 2;
		if (tmp % 10 == 0) {
			return tmp;
		}
		return tmp + (10 - tmp % 10);
	}

	private int countAdult(final List<String> passengers) {
		int result = 0;
		for (String each : passengers) {
			if (isAdult(each)) {
				result++;
			}
		}
		return result;
	}

	private void test(final String input, final String expected) {
		Busfee bf = new Busfee();
		assertEquals(expected, bf.solve(input));
	}

	@Test
	public void testBusfee() throws Exception {
		/* 0 */test("210:Cn,In,Iw,Ap,Iw", "170");
		/* 1 */test("220:Cp,In", "110");
		/* 2 */test("230:Cw,In,Iw", "240");
		/* 3 */test("240:In,An,In", "240");
		/* 4 */test("250:In,In,Aw,In", "260");
		/* 5 */test("260:In,In,In,In,Ap", "260");
		/* 6 */test("270:In,An,In,In,Ip", "410");
		/* 7 */test("280:Aw,In,Iw,In", "210");
		/* 8 */test("200:An", "200");
		/* 9 */test("210:Iw", "60");
		/* 10 */test("220:Ap", "0");
		/* 11 */test("230:Cp", "0");
		/* 12 */test("240:Cw", "60");
		/* 13 */test("250:In", "130");
		/* 14 */test("260:Cn", "130");
		/* 15 */test("270:Ip", "0");
		/* 16 */test("280:Aw", "140");
		/* 17 */test("1480:In,An,In,In,In,Iw,Cp,Cw,In,Aw,In,In,Iw,Cn,Aw,Iw",
				"5920");
		/* 18 */test("630:Aw,Cw,Iw,An,An", "1740");
		/* 19 */test("340:Cn,Cn,Ip,Ap", "340");
		/* 20 */test("240:Iw,Ap,In,Iw,Aw", "120");
		/* 21 */test("800:Cw,An,Cn,Aw,Ap", "1800");
		/* 22 */test("1210:An,Ip,In,Iw,An,Iw,Iw,An,Iw,Iw", "3630");
		/* 23 */test("530:An,Cw,Cw", "810");
		/* 24 */test("170:Aw,Iw,Ip", "90");
		/* 25 */test("150:In,Ip,Ip,Iw,In,Iw,Iw,In,An,Iw,Aw,Cw,Iw,Cw,An,Cp,Iw",
				"580");
		/* 26 */test("420:Cn,Cw,Cp", "320");
		/* 27 */test("690:Cw,In,An,Cp,Cn,In", "1220");
		/* 28 */test("590:Iw,Iw,Cn,Iw,Aw,In,In,Ip,Iw,Ip,Aw", "1200");
		/* 29 */test("790:Cw,Cn,Cn", "1000");
		/* 30 */test("1220:In,In,An,An,In,Iw,Iw,In,In,Ip,In,An,Iw", "4590");
		/* 31 */test("570:Cw,Cn,Cp", "440");
		/* 32 */test("310:Cn,Cw,An,An,Iw,Cp,Cw,Cn,Iw", "1100");
		/* 33 */test("910:Aw,In,Iw,Iw,Iw,Iw,Iw,An,Cw,In", "2290");
		/* 34 */test("460:Iw,Cw,Cw,Cn", "590");
		/* 35 */test("240:Iw,Iw,In,Iw,In,In,Cn,In,An", "780");
		/* 36 */test("1240:In,In,In,Ap,In,Cw,Iw,Iw,Iw,Aw,Cw", "2170");
		/* 37 */test(
				"1000:Iw,Ip,In,An,In,In,In,An,In,Iw,In,In,Iw,In,Iw,Iw,Iw,An",
				"5500");
		/* 38 */test("180:In,Aw,Ip,Iw,In,Aw,In,Iw,Iw,In", "330");
		/* 39 */test("440:In,Ip,Cp,Aw,Iw,In,An", "660");
		/* 40 */test("1270:Ap,In,An,Ip,In,Ip,Ip", "1270");
	}
}