堆排序算法C++实现

堆排序

#include <iostream>
#include <vector>

using namespace std;

void heapify(vector<int>& nums, int n, int i) {
	int largest = i;             //当前需要调整为堆结构的节点
	int lson = i * 2 + 1;  
	int rson = i * 2 + 2;

	if (lson < n && nums[lson] > nums[largest]) {
		largest = lson;
	}
	if (rson < n && nums[rson] > nums[largest]) {
		largest = rson;
	}

	if (largest != i) {
		swap(nums[i], nums[largest]);
		heapify(nums, n, largest);
	}
}


void heapSort(vector<int>& nums, int n) {
	//建堆
	for (int i = n / 2 - 1; i >= 0; --i) {  
		heapify(nums, n, i);  //对所有具有子节点的节点构建堆排序
	}
	//排序
	for (int i = n - 1; i > 0; --i) {
		swap(nums[i], nums[0]);
		heapify(nums, i, 0);  //将最大的节点换到最后一个位置，并在下次调整时不考虑
	}
}

int main() {

	vector<int> nums = { 1, 2, 4, 5, 3, 3, 8, 6 };
	heapSort(nums, nums.size());

	for (int& i : nums) cout << i << " ";

}