add c++11 (#87)

* binary search c++

* selection sort c++11

* c++ recursive countdown

* c++ recursion

* c++ quicksort

* rename folder names to c++11

* add another version of binary_search function

* c++11 hash tables

* c++11 breadth-first search

01_introduction_to_algorithms/c++11/01_binary_search.cpp

@@ -0,0 +1,67 @@
+#include <iostream>
+#include <vector>
+
+using std::cout;
+using std::endl;
+
+template <typename T>
+int binary_search(const std::vector<T>& list, const int& item) {
+    int low = 0;
+    int high = list.size() - 1;
+
+    while (low <= high) {
+        int mid = (low + high) / 2;
+        T guess = list[mid];
+
+        if (guess == item) {
+            return mid;
+        }
+
+        if (guess > item) {
+            high = mid - 1;
+        } else {
+            low = mid + 1;
+        }
+    }
+
+    return -1;
+}
+
+// this function returns pointer to the found element rather than array index
+template <typename T>
+const T* binary_search2(const std::vector<T>& list, const T& item) {
+    const T* low = &list.front();
+    const T* high = &list.back();
+
+    while (low <= high) {
+        // "guess" is the element in the middle between "high" and "low"
+        const T* guess = low + ((high - low) / 2);
+
+        if (*guess == item) 
+            return guess;
+        
+        if (*guess > item) {
+            high = guess - 1;
+        } else {
+            low = guess + 1;
+        }
+    }
+
+    return nullptr;
+}
+
+int main() {
+    std::vector<int> my_list = {1, 3, 5, 7, 9};
+    const int* binary_search2_result = binary_search2(my_list, 9);
+    const int* binary_search2_null = binary_search2(my_list, 4); // test finding element that is not in the list
+
+    cout << "Binary search for number 3: " << binary_search(my_list, 3) << endl;
+    cout << "Binary search 2 for number 9 (memory address): " << binary_search2_result << endl;
+    cout << "Binary search 2 for number 9 (value): " << *binary_search2_result << endl;
+    
+    if (binary_search2_null == nullptr) {
+		cout << "4 was not found in the list" << endl;
+	}
+
+    return 0;
+}

01_introduction_to_algorithms/c++11/Makefile

@@ -0,0 +1,10 @@
+CPP=g++
+CPPFLAGS=-Wall -std=c++11
+MAIN_NAME=main
+objects=01_binary_search.o
+
+main: $(objects)
+	$(CPP) -std=c++11 $(CPPFLAGS) -o $(MAIN_NAME) $(objects)
+
+clean:
+	rm -f $(MAIN_NAME) $(objects)