add Chapter06

Chapter06/priority_queue_adaptor.cpp

@@ -0,0 +1,72 @@
+#include <array>
+#include <cstdio>
+#include <queue>
+#include <stack>
+
+template <typename T, size_t S> class fixed_vector : public std::array<T, S> { 
+
+  public: 
+    void push_back(const T &el) { 
+        if(cnt_ < S) { 
+            this->at(cnt_) = el; 
+            ++cnt_; 
+        } 
+    } 
+
+    T &back() { 
+        return this->at(cnt_-1); 
+    } 
+
+    void pop_back() { 
+        if(cnt_) { 
+            --cnt_; 
+        } 
+    } 
+
+    auto end() { 
+        return std::array<T, S>::begin() + cnt_; 
+    } 
+
+    bool empty() const { 
+        return cnt_ == 0; 
+    } 
+
+  private: 
+    size_t cnt_ = 0; 
+}; 
+
+int main() { 
+
+    std::priority_queue<int, fixed_vector<int, 10>> pq; 
+
+    pq.push(10); 
+    pq.push(4); 
+    pq.push(8); 
+    pq.push(1); 
+    pq.push(2); 
+
+    printf("Popping elements from priority queue: "); 
+
+    while(!pq.empty()) { 
+       printf("%d ", pq.top()); 
+       pq.pop(); 
+    } 
+
+    std::stack<int, fixed_vector<int, 10>> st; 
+
+    st.push(10); 
+    st.push(4); 
+    st.push(8); 
+    st.push(1); 
+    st.push(2); 
+
+    printf("\r\nPopping elements from stack (LIFO): "); 
+
+    while(!st.empty()) { 
+       printf("%d ", st.top()); 
+       st.pop(); 
+    } 
+    printf("\r\n");
+  
+    return 0; 
+}