Enable the main function work by implementing the iterator interface.

Enable the main function work by implementing the iterator interface.

Author: yanglr

cpp-leetcode/leetcode284-peeking-iterator_with_main.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <queue>
+#include <vector>
+#include <assert.h>
+#include <algorithm>
+using namespace std;
+
+class Iterator {
+    const vector<int>* nums;
+    int index;
+public:
+    Iterator(const vector<int>& nums) {
+        this->nums = &nums;
+        this->index = 0;
+    }
+    Iterator(const Iterator& iter);
+    
+    // Returns the next element in the iteration.
+    int next() {
+        return (*nums)[index++];
+    }
+    
+    // Returns true if the iteration has more elements.
+    bool hasNext() const {
+        return index < (*nums).size();
+    }
+};
+
+class PeekingIterator : public Iterator {
+private:
+    int nextElement;
+    bool flag;
+public:
+	PeekingIterator(const 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.
+        flag = Iterator::hasNext();
+        if (flag) {
+            nextElement = Iterator::next();
+        }
+	}
+	
+    // Returns the next element in the iteration without advancing the iterator.
+	int peek() {
+        return nextElement;
+	}
+	
+	// hasNext() and next() should behave the same as in the Iterator interface.
+	// Override them if needed.
+	int next() {
+        int ret = nextElement;
+        flag = Iterator::hasNext();
+        if (flag) {
+            nextElement = Iterator::next();
+        }
+        return ret;
+	}
+	
+	bool hasNext() const {
+        return flag;
+	}
+};
+
+// Test
+int main()
+{
+    /** 用gcc/g++编译, 需要用这种方式初始化vector:
+    */
+    int a[3] = {1, 2, 3};
+    vector<int> nums(a, a + 3);
+
+    PeekingIterator peekingIterator(nums);
+    assert(1 == peekingIterator.next());
+    assert(2 == peekingIterator.peek());
+    assert(2 == peekingIterator.next());
+    assert(3 == peekingIterator.next());
+    assert(!peekingIterator.hasNext());
+    
+    cout << "OK~" << endl;
+    
+    return 0;
+}