C++ sort与优先队列排序的区别

  int main() {vector<int> data{3, 1, 2};cout << "从小到大排序" << endl;sort(data.begin(), data.end(), std::less<int>());printContainer(data);auto cmp1 = [](int x, int y) { return x < y; };sort(data.begin(), data.end(), cmp1);printContainer(data);cout << "从大到小排序" << endl;sort(data.begin(), data.end(), std::greater<int>());printContainer(data);auto cmp2 = [](int x, int y) { return x > y; };sort(data.begin(), data.end(), cmp2);printContainer(data);cout << "大顶堆" << endl;priority_queue<int, vector<int>, std::less<int>> heap1(data.begin(), data.end());printHeapOrStack(heap1);priority_queue<int, vector<int>, decltype(cmp1)> heap2(data.begin(), data.end());printHeapOrStack(heap2);cout << "小顶堆" << endl;priority_queue<int, vector<int>, std::greater<int>> heap3(data.begin(), data.end());printHeapOrStack(heap3);priority_queue<int, vector<int>, decltype(cmp2)> heap4(data.begin(), data.end());printHeapOrStack(heap4);
}

输出结果：

从小到大排序
1    2    3    
1    2    3    
从大到小排序
3    2    1    
3    2    1    
大顶堆
3    2    1    
3    2    1    
小顶堆
1    2    3    
1    2    3    

可以看到：std::sort 与 优先队列的排序规则刚好相反。

另外：本文使用的一些辅助打印容器函数备忘：

template<typename Container>
void printContainer(const Container &container) {for (const auto &item: container) {std::cout << item << "\t";}std::cout << std::endl;
}template<typename Container>
void printHeapOrStack(const Container &heap) {Container heapCopy = heap;while (!heapCopy.empty()) {std::cout << heapCopy.top() << "\t";heapCopy.pop();}std::cout << std::endl;
}template <typename MapType>
void printMap(const MapType& container) {for (const auto& item : container) {std::cout << item.first << ": " << item.second << "\t";}std::cout << std::endl;
}template <typename QueueType>
void printQueue(const std::queue<QueueType>& q) {std::queue<QueueType> qCopy = q;while (!qCopy.empty()) {std::cout << qCopy.front() << "\t";qCopy.pop();}std::cout << std::endl;
}