[C++ STL] priority_queue example

stl_priority_queue_example.cpp

#include <iostream>
#include <queue>
using namespace std;

class Node{
public:
	int val;
	Node* left;
	Node* right;	
	Node (int v, Node *l, Node *r) : val(v), left(l), right(r) {;}
};

struct compare{
	bool operator()(const Node* l, const Node* r){
		return l->val < r->val;
	}
};

int main()
{
	// 01. Simple integer max priroity queue example
	int ints[] = {1,5,2,3,63,63,4,24,12,4123,42};
	vector<int> vi(ints, ints + sizeof(ints)/sizeof(int));
	priority_queue<int> intMaxPQ;

	for (int i : vi)
		intMaxPQ.push(i);

	while (!intMaxPQ.empty()){
		cout << intMaxPQ.top() << " ";
		intMaxPQ.pop();
	}
	cout << endl;
    	// 4123 63 63 42 24 12 5 4 3 2 1
	
	// 02. Simple integer min priroity queue example
	priority_queue<int, vector<int>, std::greater<int> > intMinPQ;
	
	for (int i : vi)
		intMinPQ.push(i);

	while (!intMinPQ.empty()){
		cout << intMinPQ.top() << " ";
		intMinPQ.pop();
	}
	cout << endl;
    	// 1 2 3 4 5 12 24 42 63 63 4123

	// 03. customized priority queue example
	priority_queue<int, vector<Node*>, compare> nodePQ;

	for (int i : vi){
		Node* n = new Node(i, nullptr, nullptr);
		nodePQ.push(n);
	}

	while (!nodePQ.empty()){
		cout << nodePQ.top()->val << " ";
		nodePQ.pop();
	}
	cout << endl;
    	// 4123 63 63 42 24 12 5 4 3 2 1
                                
}