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algorithm_heap_04.cc
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algorithm_heap_04.cc
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//
// Program
// <algorithm> @ make_heap for a custom object.
//
// Compile
// g++ -Wall -Wextra -pedantic -std=c++17 -o algorithm_heap_04 algorithm_heap_04.cc
//
// Execution
// ./algorithm_heap_04
//
#include <algorithm>
#include <iostream>
#include <vector>
constexpr int size = 5;
struct pack {
int ival;
float fval;
};
static std::ostream& operator<< (std::ostream& out, const pack& p) {
out << "{" << p.ival << "," << p.fval << "}";
return out;
}
// Return true if lhs is smaller than rhs
struct Comparator {
bool operator () (const pack &lhs, const pack &rhs) {
return (lhs.fval < rhs.fval);
}
};
//
// Entry function
//
int main() {
std::cout <<"\n--- [make_heap] ---\n";
{
std::vector<pack> vec(size);
for (int i = 0; i < size; ++i) {
vec[i].ival = i + 1;
vec[i].fval = i + 2.1f;
}
std::cout << "[Input]\n";
for (const auto& item: vec) {
std::cout << " " << item << '\n';
}
std::cout << "is_heap: " << std::boolalpha
<< std::is_heap(vec.begin(), vec.end(), Comparator{})
<< '\n';
std::cout << "Call make_heap...\n";
// Arrange our vector into Max Heap arrangement
std::make_heap(vec.begin(), vec.end(), Comparator{});
std::cout << "[Input]\n";
for (const auto& item: vec) {
std::cout << " " << item << '\n';
}
std::cout << "is_heap: " << std::boolalpha
<< std::is_heap(vec.begin(), vec.end(), Comparator{})
<< '\n';
}
return 0;
}
/*
--- [make_heap] ---
[Input]
{1,2.1}
{2,3.1}
{3,4.1}
{4,5.1}
{5,6.1}
is_heap: false
Call make_heap...
[Input]
{5,6.1}
{4,5.1}
{3,4.1}
{1,2.1}
{2,3.1}
is_heap: true
*/