go语言最小堆最大堆堆排序

建堆
调整
删除
先根据数组构建完全二叉树
在这里插入图片描述
从第一个非叶结点开始调整为大跟堆，这里就是图里面的1结点开始调整

代码如下：

func findKthLargest(nums []int, k int) int {heapSize := len(nums)buildMaxHeap(nums,heapSize)for i := len(nums) - 1; i >= len(nums) - k + 1; i-- {//堆顶出列 堆低补上nums[0], nums[i] = nums[i], nums[0]heapSize--maxHeapify(nums,0,heapSize)}return nums[0]
}
func buildMaxHeap(a []int, heapSize int) {//初始化大根堆//非叶结点都堆排序一次 排序方式从尾到头for i := heapSize / 2; i >= 0; i-- {maxHeapify(a,i,heapSize)}
}
// 大跟堆的调整
// 传入一个非叶结点
func maxHeapify(a []int, i ,heapSize int) {l := i*2 + 1r := i*2 + 2largest := iif l < heapSize && a[l] > a[largest] {largest = l}if r < heapSize && a[r] > a[largest] {largest = r}if largest != i {a[i], a[largest] = a[largest], a[i]//交换后的元素需要继续堆化maxHeapify(a,largest,heapSize)}
}

以此类推运用上一个模板来再写一题
前K个高频元素

func topKFrequent(nums []int, k int) []int {res := []int{}hash := map[int]int{}for i := range nums {hash[nums[i]]++}//创建新数组new := []int{}for key := range hash {new = append(new,key)}heapSize := len(new)buildHeap(new, heapSize, hash)for i := len(new) - 1; i >= len(new) - k; i-- {res = append(res,new[0])new[0], new[i] = new[i], new[0]heapSize--heapify(new,0,heapSize, hash)}return res
}
func buildHeap(a []int, heapSize int, hash map[int]int) {for i := heapSize / 2; i >= 0; i-- {heapify(a,i,heapSize, hash)}
}func heapify(a []int, i int, heapSize int, hash map[int]int) {l := i*2 + 1r := i*2 + 2largest := iif l < heapSize && hash[a[l]] > hash[a[largest]] {largest = l}if r < heapSize && hash[a[r]] > hash[a[largest]] {largest = r}if largest != i {a[i], a[largest] = a[largest], a[i]heapify(a,largest,heapSize, hash)}
}