problems: add an RLE Iterator

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/rle-iterator.java

@@ -0,0 +1,55 @@
+class RLEIterator {
+    private int[] encoding;
+    private int major = 0;
+    private int minor = 0;
+
+    public RLEIterator(int[] encoding) {
+        this.encoding = encoding;
+    }
+
+    private void nextSegment() {
+        major += 2;
+        minor = 0;
+    }
+
+    private int lastConsumed() {
+        if (major == 0 && minor == 0) {
+            // Haven't consumed anything
+            return -1;
+        } else if (major <= encoding.length && minor == 0) {
+            // Consumed last element of a previous segment
+            return encoding[major - 1];
+        } else if (major >= encoding.length) {
+            // Everything was consumed
+            return -1;
+        }
+
+        // Last consumed from the current segment
+        return encoding[major + 1];
+    }
+
+    public int next(int n) {
+        while (n > 0 && major < encoding.length) {
+            int consumed = Math.min(n, encoding[major] - minor);
+
+            n -= consumed;
+            minor += consumed;
+
+            if (minor == encoding[major]) {
+                nextSegment();
+            }
+        }
+
+        if (n > 0) {
+            return -1;
+        }
+
+        return lastConsumed();
+    }
+}
+
+/**
+ * Your RLEIterator object will be instantiated and called as such:
+ * RLEIterator obj = new RLEIterator(encoding);
+ * int param_1 = obj.next(n);
+ */