From 491c2dee55bdc9575dc5a52965a78348937685b6 Mon Sep 17 00:00:00 2001
From: Jinyoung Jeong <80400463+jyoung2419@users.noreply.github.com>
Date: Sat, 19 Sep 2026 22:58:26 +0900
Subject: [PATCH] Implement PeekingIterator for iterator functionality

---
 .../284. Peeking Iterator"                    | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 "leetcode3/\354\240\225\354\247\204\354\230\201/284. Peeking Iterator"

diff --git "a/leetcode3/\354\240\225\354\247\204\354\230\201/284. Peeking Iterator" "b/leetcode3/\354\240\225\354\247\204\354\230\201/284. Peeking Iterator"
new file mode 100644
index 00000000..bb2cf35f
--- /dev/null
+++ "b/leetcode3/\354\240\225\354\247\204\354\230\201/284. Peeking Iterator"	
@@ -0,0 +1,56 @@
+/**
+ * // This is the Iterator's API interface.
+ * // You should not implement it, or speculate about its implementation.
+ * function Iterator() {
+ *    @ return {number}
+ *    this.next = function() { // return the next number of the iterator
+ *       ...
+ *    }; 
+ *
+ *    @return {boolean}
+ *    this.hasNext = function() { // return true if it still has numbers
+ *       ...
+ *    };
+ * };
+ */
+
+/**
+ * @param {Iterator} iterator
+ */
+var PeekingIterator = function(iterator) {
+    this.iterator = iterator;
+
+    this.nextValue = iterator.hasNext() ? iterator.next() : null;
+};
+
+/**
+ * @return {number}
+ */
+PeekingIterator.prototype.peek = function() {
+    return this.nextValue;
+};
+
+/**
+ * @return {number}
+ */
+PeekingIterator.prototype.next = function() {
+    const ans = this.nextValue;
+
+    this.nextValue = this.iterator.hasNext() ? this.iterator.next() : null;
+    return ans;
+};
+
+/**
+ * @return {boolean}
+ */
+PeekingIterator.prototype.hasNext = function() {
+    return this.nextValue !== null;
+};
+
+/** 
+ * Your PeekingIterator object will be instantiated and called as such:
+ * var obj = new PeekingIterator(arr)
+ * var param_1 = obj.peek()
+ * var param_2 = obj.next()
+ * var param_3 = obj.hasNext()
+ */