mirror of
https://github.com/halfrost/LeetCode-Go.git
synced 2025-07-24 19:04:32 +08:00
88 lines
1.6 KiB
Go
88 lines
1.6 KiB
Go
package leetcode
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import (
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"container/heap"
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)
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// 解法一 二分搜索
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func kthSmallest378(matrix [][]int, k int) int {
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m, n, low := len(matrix), len(matrix[0]), matrix[0][0]
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high := matrix[m-1][n-1] + 1
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for low < high {
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mid := low + (high-low)>>1
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// 如果 count 比 k 小，在大值的那一半继续二分搜索
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if counterKthSmall(m, n, mid, matrix) >= k {
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high = mid
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} else {
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low = mid + 1
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}
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}
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return low
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}
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func counterKthSmall(m, n, mid int, matrix [][]int) int {
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count, j := 0, n-1
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// 每次循环统计比 mid 值小的元素个数
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for i := 0; i < m; i++ {
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// 遍历每行中比 mid 小的元素的个数
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for j >= 0 && mid < matrix[i][j] {
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j--
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}
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count += j + 1
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}
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return count
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}
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// 解法二 优先队列
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func kthSmallest3781(matrix [][]int, k int) int {
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if len(matrix) == 0 || len(matrix[0]) == 0 {
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return 0
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}
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pq := &pq{data: make([]interface{}, k)}
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heap.Init(pq)
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for i := 0; i < len(matrix); i++ {
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for j := 0; j < len(matrix[0]); j++ {
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if pq.Len() < k {
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heap.Push(pq, matrix[i][j])
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} else if matrix[i][j] < pq.Head().(int) {
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heap.Pop(pq)
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heap.Push(pq, matrix[i][j])
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} else {
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break
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}
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}
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}
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return heap.Pop(pq).(int)
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}
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type pq struct {
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data []interface{}
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len int
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}
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func (p *pq) Len() int {
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return p.len
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}
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func (p *pq) Less(a, b int) bool {
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return p.data[a].(int) > p.data[b].(int)
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}
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func (p *pq) Swap(a, b int) {
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p.data[a], p.data[b] = p.data[b], p.data[a]
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}
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func (p *pq) Push(o interface{}) {
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p.data[p.len] = o
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p.len++
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}
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func (p *pq) Head() interface{} {
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return p.data[0]
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}
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func (p *pq) Pop() interface{} {
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p.len--
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return p.data[p.len]
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}
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