add: 220425 [cpp]

cpp/2204/220425.cpp

@@ -0,0 +1,75 @@
+#include <vector>
+
+/*
+ * Below is the interface for Iterator, which is already defined for you.
+ * **DO NOT** modify the interface for Iterator.
+ */
+class Iterator {
+	struct Data;
+	Data* data;
+public:
+	Iterator(const std::vector<int>& nums);
+
+	Iterator(const Iterator& iter);
+
+	// Returns the next element in the iteration.
+	int next();
+
+// Returns true if the iteration has more elements.
+	bool hasNext() const;
+};
+
+/**
+ * 284. Peeking Iterator
+ * Design an iterator that supports the peek operation on an existing iterator in addition to the hasNext and the next operations.
+ *
+ * Implement the PeekingIterator class:
+ *
+ * PeekingIterator(Iterator<int> nums) Initializes the object with the given integer iterator iterator.
+ * int next() Returns the next element in the array and moves the pointer to the next element.
+ * boolean hasNext() Returns true if there are still elements in the array.
+ * int peek() Returns the next element in the array without moving the pointer.
+ * Note: Each language may have a different implementation of the constructor and Iterator, but they all support the int next() and boolean hasNext() functions.
+ */
+
+class PeekingIterator : public Iterator {
+private:
+	int x = 0;
+	bool isEmpty = false;
+
+public:
+	explicit PeekingIterator(const std::vector<int>& nums) : Iterator(nums) {
+		// Initialize any member here.
+		// **DO NOT** save a copy of nums and manipulate it directly.
+		// You should only use the Iterator interface methods.
+		if (!Iterator::hasNext())
+			isEmpty = true;
+		else
+			this->x = Iterator::next();
+	}
+
+	// Returns the next element in the iteration without advancing the iterator.
+	int peek() const {
+		return x;
+	}
+
+	// hasNext() and next() should behave the same as in the Iterator interface.
+	// Override them if needed.
+	int next() {
+		if (this->isEmpty)
+			return -1;
+		auto ret = this->x;
+
+		if (Iterator::hasNext()) {
+			this->x = Iterator::next();
+		} else {
+			this->isEmpty = true;
+		}
+
+		return ret;
+	}
+
+	bool hasNext() const {
+		return !this->isEmpty;
+	}
+};

cpp/2204/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2204)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220424-CN.cpp)
+ADD_EXECUTABLE(2204 220425.cpp)