Problem 4.1 and 4.2 TADM

shekhargulati · shekhargulati · commit 0efdd756dd06 · 2016-04-02T22:50:06.000+05:30
diff --git a/java8/src/main/java/com/shekhargulati/IntPair.java b/java8/src/main/java/com/shekhargulati/IntPair.java
@@ -0,0 +1,36 @@
+package com.shekhargulati;
+
+import java.util.Objects;
+
+public class IntPair {
+
+    public int first;
+    public int second;
+
+    public IntPair(int first, int second) {
+        this.first = first;
+        this.second = second;
+    }
+
+    @Override
+    public String toString() {
+        return "IntPair{" +
+                "first=" + first +
+                ", second=" + second +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        IntPair intPair = (IntPair) o;
+        return first == intPair.first &&
+                second == intPair.second;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(first, second);
+    }
+}
diff --git a/java8/src/main/java/com/shekhargulati/tadm/ch04/excercises/Problem4_1.java b/java8/src/main/java/com/shekhargulati/tadm/ch04/excercises/Problem4_1.java
@@ -0,0 +1,48 @@
+package com.shekhargulati.tadm.ch04.excercises;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+public class Problem4_1 {
+
+    public static List<List<Player>> teams(List<Player> players) {
+        List<Player> sorted = players.stream().sorted((p1, p2) -> p1.rating - p2.rating).collect(Collectors.toList());
+        int totalPlayers = players.size();
+        return Arrays.asList(sorted.subList(0, totalPlayers / 2), sorted.subList(totalPlayers / 2, totalPlayers));
+    }
+
+}
+
+class Player {
+    String name;
+    int rating;
+
+    public Player(String name, int rating) {
+        this.name = name;
+        this.rating = rating;
+    }
+
+    @Override
+    public String toString() {
+        return "Player{" +
+                "name='" + name + '\'' +
+                ", rating=" + rating +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Player player = (Player) o;
+        return rating == player.rating &&
+                Objects.equals(name, player.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, rating);
+    }
+}
diff --git a/java8/src/main/java/com/shekhargulati/tadm/ch04/excercises/Problem4_2.java b/java8/src/main/java/com/shekhargulati/tadm/ch04/excercises/Problem4_2.java
@@ -0,0 +1,39 @@
+package com.shekhargulati.tadm.ch04.excercises;
+
+import com.shekhargulati.IntPair;
+
+import java.util.OptionalInt;
+import java.util.stream.IntStream;
+
+public class Problem4_2 {
+
+    public static IntPair maximize_unsorted(int[] numbers) {
+        OptionalInt min = IntStream.of(numbers).min();
+        OptionalInt max = IntStream.of(numbers).max();
+        return new IntPair(min.getAsInt(), max.getAsInt());
+    }
+
+    public static IntPair maximize_sorted(int[] numbers) {
+        return new IntPair(numbers[0], numbers[numbers.length - 1]);
+    }
+
+    public static IntPair minimize_unsorted(int[] numbers) {
+        int[] sorted = IntStream.of(numbers).sorted().toArray();
+        return minimize_sorted(sorted);
+    }
+
+    public static IntPair minimize_sorted(int[] sorted) {
+        int diff = sorted[1] - sorted[0];
+        IntPair pair = null;
+        for (int i = 1; i < sorted.length - 1; i++) {
+            int first = sorted[i];
+            int second = sorted[i + 1];
+            if (diff > (second - first)) {
+                diff = second - first;
+                pair = new IntPair(first, second);
+            }
+        }
+        return pair;
+    }
+
+}
diff --git a/java8/src/test/java/com/shekhargulati/tadm/ch04/excercises/Problem4_1Test.java b/java8/src/test/java/com/shekhargulati/tadm/ch04/excercises/Problem4_1Test.java
@@ -0,0 +1,22 @@
+package com.shekhargulati.tadm.ch04.excercises;
+
+import org.hamcrest.CoreMatchers;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertThat;
+
+public class Problem4_1Test {
+
+    @Test
+    public void shouldDistributePlayersIntoTwoUnfairTeams() throws Exception {
+        List<Player> players = Arrays.asList(new Player("a", 10), new Player("b", 7), new Player("c", 11), new Player("d", 2), new Player("e", 4), new Player("f", 15));
+
+        List<List<Player>> teams = Problem4_1.teams(players);
+        assertThat(teams.get(0), CoreMatchers.equalTo(Arrays.asList(new Player("d", 2), new Player("e", 4), new Player("b", 7))));
+        assertThat(teams.get(1), CoreMatchers.equalTo(Arrays.asList(new Player("a", 10), new Player("c", 11), new Player("f", 15))));
+
+    }
+}
diff --git a/java8/src/test/java/com/shekhargulati/tadm/ch04/excercises/Problem4_2Test.java b/java8/src/test/java/com/shekhargulati/tadm/ch04/excercises/Problem4_2Test.java
@@ -0,0 +1,42 @@
+package com.shekhargulati.tadm.ch04.excercises;
+
+import com.shekhargulati.IntPair;
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+public class Problem4_2Test {
+
+    @Test
+    public void shouldFindPairThatMaximizeWithinUnsortedArray() throws Exception {
+        int[] numbers = {6, 13, 19, 3, 8};
+
+        IntPair p = Problem4_2.maximize_unsorted(numbers);
+        assertThat(p, equalTo(new IntPair(3, 19)));
+    }
+
+    @Test
+    public void shouldFindPairThatMaximizeWithinSortedArray() throws Exception {
+        int[] numbers = {3, 6, 8, 13, 19};
+
+        IntPair p = Problem4_2.maximize_sorted(numbers);
+        assertThat(p, equalTo(new IntPair(3, 19)));
+    }
+
+    @Test
+    public void shouldFindPairThatMinimizeWithinUnsortedArray() throws Exception {
+        int[] numbers = {6, 13, 19, 3, 8, 14};
+
+        IntPair p = Problem4_2.minimize_unsorted(numbers);
+        assertThat(p, equalTo(new IntPair(13, 14)));
+    }
+
+    @Test
+    public void shouldFindPairThatMinimiseWithinSortedArray() throws Exception {
+        int[] numbers = {3, 6, 8, 13, 19};
+
+        IntPair p = Problem4_2.minimize_sorted(numbers);
+        assertThat(p, equalTo(new IntPair(6, 8)));
+    }
+}
