min heap priority queue c++
#include<queue>
std::priority_queue <int, std::vector<int>, std::greater<int> > minHeap;min heap priority queue c++
#include<queue>
std::priority_queue <int, std::vector<int>, std::greater<int> > minHeap;priority queue with min heap
This is frequently used in Competitive Programming.
We first multiply all elements with (-1). Then we create a max heap (max heap is the default for priority queue).
When we access the data and want to print it we simply multiply those elements with (-1) again.priority queue max heap in java
//Sol1
PriorityQueue<Integer> queue = new PriorityQueue<>(10, Collections.reverseOrder());
//Sol2
// PriorityQueue<Integer> pq = new PriorityQueue<>((x, y) -> y - x);
PriorityQueue<Integer> pq =new PriorityQueue<>((x, y) -> Integer.compare(y, x));
//Sol3
PriorityQueue<Integer> pq = new PriorityQueue<Integer>(defaultSize, new Comparator<Integer>() {
public int compare(Integer lhs, Integer rhs) {
if (lhs < rhs) return +1;
if (lhs.equals(rhs)) return 0;
return -1;
}
});Difference between Priority Queue and Heap
This website provides a really clear explanation. http://pages.cs.wisc.edu/~vernon/cs367/notes/11.PRIORITY-Q.html
In short, a priority queue can be implemented using many of the data structures that we've already studied (an array, a linked list, or a binary search tree). However, those data structures do not provide the most efficient operations. To make all of the operations very efficient, we'll use a new data structure called a heap.Priority Queue using Min Heap in c++
#include <bits/stdc++.h>
using namespace std;
int main ()
{
priority_queue <int> pq;
pq.push(5);
pq.push(1);
pq.push(10);
pq.push(30);
pq.push(20);
while (pq.empty() == false)
{
cout << pq.top() << " ";
pq.pop();
}
return 0;
}Copyright © 2021 Codeinu
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