67 lines
1.2 KiB
Go
67 lines
1.2 KiB
Go
package main
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//数字表
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type NumberTable struct {
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key int
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val int
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}
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//构建最小堆
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func minHeap(heap []NumberTable, k int) {
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for i := k/2 - 1; i >= 0; i-- {
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if heap[i].val > heap[(i+1)*2-1].val {
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tmp := heap[i]
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heap[i] = heap[(i+1)*2-1]
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heap[(i+1)*2-1] = tmp
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//0123
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//1234
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}
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if k > (i+1)*2 && heap[i].val > heap[(i+1)*2].val {
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tmp := heap[i]
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heap[i] = heap[(i+1)*2]
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heap[(i+1)*2] = tmp
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}
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}
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}
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func topKFrequent(nums []int, k int) []int {
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//hashmap计算各个数字次数
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var numMap = make(map[int]int)
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for _, val := range nums {
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numMap[val]++
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}
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//构建优先队列
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var heap = make([]NumberTable, k)
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var i = 0
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for key, val := range numMap {
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if i >= k {
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break
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}
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heap[i] = NumberTable{key, val}
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i++
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numMap[key] = 0
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}
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//构建一次最小堆
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minHeap(heap, k)
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for key, val := range numMap {
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if val == 0 {
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continue
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}
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//后面的继续进入堆,对比第一个位置
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if heap[0].val < val {
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heap[0] = NumberTable{key, val}
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minHeap(heap, k)
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}
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}
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var ret []int
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for _, val := range heap {
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ret = append(ret, val.key)
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}
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return ret
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}
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func main() {
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topKFrequent([]int{5, -3, 9, 1, 7, 7, 9, 10, 2, 2, 10, 10, 3, -1, 3, 7, -9, -1, 3, 3}, 3)
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}
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