Merge pull request #2093 from shawnw/challenge-074-solution

Solutions for challenge 074.

2 files changed, 57 insertions, 0 deletions

diff --git a/challenge-074/shawn-wagner/java/ch1.java b/challenge-074/shawn-wagner/java/ch1.java
new file mode 100644
index 0000000000..7d14236d22
--- /dev/null
+++ b/challenge-074/shawn-wagner/java/ch1.java
@@ -0,0 +1,26 @@
+// Use streams to calculate the count of distinct elements in an array and
+// filter out just the first one above the cutoff.
+
+// I'm particularly proud of this one.
+
+import java.util.*;
+import java.util.stream.*;
+import java.util.function.Function;
+
+class ch1 {
+    private static void task1(int[] a) {
+        int cutoff = (int)Math.floor(a.length / 2.0);
+        int over_cutoff =
+            Arrays.stream(a).boxed()
+            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
+            .entrySet().stream()
+            .filter(entry -> entry.getValue() > cutoff)
+            .findFirst().map(entry -> entry.getKey()).orElse(-1);
+        System.out.println(over_cutoff);
+    }
+
+    public static void main(String[] args) {
+        task1(new int[] {1, 2, 2, 3, 2, 4, 2});
+        task1(new int[] {1, 3, 1, 2, 4, 5});
+    }
+}
diff --git a/challenge-074/shawn-wagner/java/ch2.java b/challenge-074/shawn-wagner/java/ch2.java
new file mode 100644
index 0000000000..65a8a04a67
--- /dev/null
+++ b/challenge-074/shawn-wagner/java/ch2.java
@@ -0,0 +1,31 @@
+// Same algorithm as the perl version, using a LinkedHashMap to
+// preserve order of keys, and streams to avoid most loops.
+
+import java.util.*;
+
+class ch2 {
+    private static void task2(String s) {
+        ArrayList<Character> chars = new ArrayList<Character>();
+        chars.ensureCapacity(s.length());
+        s.chars().forEach(ch -> chars.add((char)ch));
+        Collections.reverse(chars);
+        StringBuilder sb = new StringBuilder();
+        while (chars.size() > 0) {
+            HashMap<Character, Integer> counts =
+                new LinkedHashMap<Character, Integer>();
+            chars.stream().forEach(ch -> counts.put(ch, counts.getOrDefault(ch, 0) + 1));
+            char fnr = counts.entrySet().stream()
+                .filter(entry -> entry.getValue() == 1)
+                .findFirst().map(entry -> entry.getKey()).orElse('#');
+            sb.append(fnr);
+            chars.remove(0);
+        }
+        sb.reverse();
+        System.out.println(sb);
+    }
+
+    public static void main(String[] args) {
+        task2("ababc");
+        task2("xyzzyx");
+    }
+}