Initial data commit

Task/Stem-and-leaf-plot/Java/stem-and-leaf-plot-2.java

@@ -0,0 +1,85 @@
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public interface StemAndLeaf {
+  public static final int[] data = {12, 127, 28, 42, 39, 113, 42, 18, 44, 118,
+    44, 37, 113, 124, 37, 48, 127, 36, 29, 31, 125, 139, 131, 115, 105,
+    132, 104, 123, 35, 113, 122, 42, 117, 119, 58, 109, 23, 105, 63,
+    27, 44, 105, 99, 41, 128, 121, 116, 125, 32, 61, 37, 127, 29, 113,
+    121, 58, 114, 126, 53, 114, 96, 25, 109, 7, 31, 141, 46, 13, 27,
+    43, 117, 116, 27, 7, 68, 40, 31, 115, 124, 42, 128, 52, 71, 118,
+    117, 38, 27, 106, 33, 117, 116, 111, 40, 119, 47, 105, 57, 122,
+    109, 124, 115, 43, 120, 43, 27, 27, 18, 28, 48, 125, 107, 114, 34,
+    133, 45, 120, 30, 127, 31, 116, 146};
+
+  public static Map<Integer, List<Integer>> createPlot(int... data) {
+    Map<Integer, List<Integer>> plot = Arrays.stream(data)
+      .parallel()
+      .boxed()
+      .collect(
+        Collectors.groupingBy(
+          datum -> datum / 10, // stem, integer division
+          Collectors.mapping(
+            datum -> datum % 10, // leaf
+            Collectors.toList()
+          )
+        )
+      )
+    ;
+    int highestStem = Arrays.stream(data)
+      .parallel()
+      .map(datum -> datum / 10)
+      .max()
+      .orElse(-1) //for filling in stems with no leaves
+    ;
+    Optional.of(plot)
+      .map(Map::keySet)
+      .map(Collection::size)
+      .filter(size -> size < highestStem + 1 /*highest stem value and 0*/)
+      .ifPresent(p ->
+        IntStream.rangeClosed(
+          0,
+          highestStem
+        )
+          .parallel()
+          .forEach(i ->
+            plot.computeIfAbsent(i, $ -> new LinkedList<>())
+          )
+      )
+    ;
+    return plot;
+  }
+
+  public static void printPlot(Map<Integer, List<Integer>> plot) {
+    plot.entrySet()
+      .stream()
+      .parallel()
+      .peek(line -> Optional.of(line)
+        .map(Map.Entry::getValue)
+        .ifPresent(Collections::sort)
+      )
+      .map(line ->
+        String.join(" ",
+          String.valueOf(line.getKey()),
+          "|",
+          String.valueOf(line.getValue())
+        )
+      )
+      .forEachOrdered(System.out::println)
+    ;
+  }
+
+  public static void main(String... arguments) {
+    Optional.of(data)
+      .map(StemAndLeaf::createPlot)
+      .ifPresent(StemAndLeaf::printPlot)
+    ;
+  }
+}