c-resources/CPlusPlus20ForProgrammers-m.../examples/ch14/fig14_15.cpp

79 lines
3.0 KiB
C++

// fig14_15.cpp
// Algorithms make_heap, sort_heap, push_heap and pop_heap.
#include <iostream>
#include <algorithm>
#include <array>
#include <vector>
#include <iterator>
int main() {
std::ostream_iterator<int> output{std::cout, " "};
std::array heapArray{3, 100, 52, 77, 22, 31, 1, 98, 13, 40};
std::cout << "heapArray before make_heap:\n";
std::ranges::copy(heapArray, output);
std::ranges::make_heap(heapArray); // create heap from heapArray
std::cout << "\nheapArray after make_heap:\n";
std::ranges::copy(heapArray, output);
std::ranges::sort_heap(heapArray); // sort elements with sort_heap
std::cout << "\nheapArray after sort_heap:\n";
std::ranges::copy(heapArray, output);
// lambda to add an int to a heap
auto push{
[&](std::vector<int>& heap, int value) {
std::cout << "\n\npushing " << value << " onto heap";
heap.push_back(value); // add value to the heap
std::ranges::push_heap(heap); // insert last element into heap
std::cout << "\nheap: ";
std::ranges::copy(heap, output);
}
};
// lambda to remove an item from the heap
auto pop{
[&](std::vector<int>& heap) {
std::ranges::pop_heap(heap); // remove max item from heap
std::cout << "\n\npopping highest priority item: " << heap.back();
heap.pop_back(); // remove vector's last element
std::cout << "\nheap: ";
std::ranges::copy(heap, output);
}
};
std::vector<int> heapVector{};
// place five integers into heapVector, maintaining it as a heap
for (auto value : {3, 52, 100}) {
push(heapVector, value);
}
pop(heapVector); // remove max item
push(heapVector, 22); // add new item to heap
pop(heapVector); // remove max item
push(heapVector, 77); // add new item to heap
pop(heapVector); // remove max item
pop(heapVector); // remove max item
pop(heapVector); // remove max item
std::cout << "\n";
}
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* (C) Copyright 1992-2021 by Deitel & Associates, Inc. and *
* Pearson Education, Inc. All Rights Reserved. *
* *
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