From a71684d500cf0eb2eb4ce7dc0396ae91a80e5ddc Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Fri, 5 Aug 2022 12:11:01 +0200
Subject: [PATCH] problems: add peeking iterator

Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 problems/peeking-iterator.java | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 problems/peeking-iterator.java

diff --git a/problems/peeking-iterator.java b/problems/peeking-iterator.java
new file mode 100644
index 0000000..98440f7
--- /dev/null
+++ b/problems/peeking-iterator.java
@@ -0,0 +1,32 @@
+class PeekingIterator implements Iterator<Integer> {
+    private Iterator<Integer> it;
+
+    private Integer pVal;
+    private boolean pHasNext;
+
+    public PeekingIterator(Iterator<Integer> iterator) {
+        it = iterator;
+        next();
+    }
+
+    public Integer peek() {
+        return pVal;
+    }
+
+    @Override
+    public Integer next() {
+        pHasNext = it.hasNext();
+
+        Integer oldValue = pVal;
+        if (pHasNext) {
+            pVal = it.next();
+        }
+
+        return oldValue;
+    }
+
+    @Override
+    public boolean hasNext() {
+        return pHasNext;
+    }
+}