From 6a28e75202feca3017c26381436bbdaca561cb30 Mon Sep 17 00:00:00 2001
From: PrakarshKamal <kamalp@mcmaster.ca>
Date: Mon, 4 May 2026 01:06:23 -0400
Subject: [PATCH] Complete Competitive-Coding-10

---
 BestTimeBuySellStockII.java | 13 ++++++
 PeekingIterator.java        | 84 +++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 BestTimeBuySellStockII.java
 create mode 100644 PeekingIterator.java

diff --git a/BestTimeBuySellStockII.java b/BestTimeBuySellStockII.java
new file mode 100644
index 0000000..d094f10
--- /dev/null
+++ b/BestTimeBuySellStockII.java
@@ -0,0 +1,13 @@
+// Greedy O(n) time, O(1) space
+class Solution {
+    public int maxProfit(int[] prices) {
+        int maxProfit = 0;
+
+        for (int i = 1; i < prices.length; i++) {
+            if (prices[i] > prices[i-1]) {
+                maxProfit += prices[i] - prices[i-1];
+            }
+        }
+        return maxProfit;
+    }
+}
\ No newline at end of file
diff --git a/PeekingIterator.java b/PeekingIterator.java
new file mode 100644
index 0000000..4542249
--- /dev/null
+++ b/PeekingIterator.java
@@ -0,0 +1,84 @@
+// Java Iterator interface reference:
+// https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
+
+// Brute force O(n) time, O(n) space
+// class PeekingIterator implements Iterator<Integer> {
+
+//     List<Integer> list;
+//     int idx;
+
+// 	public PeekingIterator(Iterator<Integer> iterator) {
+// 	    // initialize any member here.
+// 	    this.list = new ArrayList<>();
+//         this.idx = 0;
+
+//         while (iterator.hasNext()) {
+//             list.add(iterator.next());
+//         }
+// 	}
+	
+//     // Returns the next element in the iteration without advancing the iterator.
+// 	public Integer peek() {
+//         return list.get(idx);
+// 	}
+	
+// 	// hasNext() and next() should behave the same as in the Iterator interface.
+// 	// Override them if needed.
+// 	@Override
+// 	public Integer next() {
+//         int val = list.get(idx);
+//         idx++;
+// 	    return val;
+// 	}
+	
+// 	@Override
+// 	public boolean hasNext() {
+// 	    return idx < list.size();
+// 	}
+// }
+
+
+// O(1) time, O(1) space
+
+import java.util.*;
+
+class PeekingIterator implements Iterator<Integer> {
+
+    Iterator<Integer> itr;
+    Integer nextVal;
+
+	public PeekingIterator(Iterator<Integer> iterator) {
+	    // initialize any member here.
+	    this.itr = iterator;
+        if (itr.hasNext()) {
+            nextVal = itr.next();
+        }
+        else {
+            nextVal = null;
+        }
+	}
+	
+    // Returns the next element in the iteration without advancing the iterator.
+	public Integer peek() {
+        return nextVal;
+	}
+	
+	// hasNext() and next() should behave the same as in the Iterator interface.
+	// Override them if needed.
+	@Override
+	public Integer next() {
+        Integer temp = nextVal;
+        if (itr.hasNext()) {
+            nextVal = itr.next();
+        }
+        else {
+            nextVal = null;
+        }
+        return temp;
+	}
+	
+	@Override
+	public boolean hasNext() {
+	    return nextVal != null;
+	}
+}
\ No newline at end of file