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218.skyline.go
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218.skyline.go
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package priorityqueue
import (
"container/heap"
"sort"
)
/*
218. The Skyline Problem
https://leetcode.com/problems/the-skyline-problem/
*/
func getSkyline(buildings [][]int) [][]int {
result := [][]int{}
sortedBuildings := sortBuildings(buildings)
pq := NewPriorityQueue()
pq.Push(0)
for _, sb := range sortedBuildings {
height := sb[1]
if height > 0 {
if height > pq.Peek() {
result = append(result, []int{sb[0], height})
}
pq.Push(height)
} else {
pq.RemoveOnce(-height)
if pq.Peek() < -height {
result = append(result, []int{sb[0], pq.Peek()})
}
}
}
return result
}
func sortBuildings(buildings [][]int) (r [][]int) {
for _, b := range buildings {
r = append(r, []int{b[0], b[2]})
r = append(r, []int{b[1], -b[2]})
}
sort.Slice(r, func(i, j int) bool {
if r[i][0] != r[j][0] {
return r[i][0] < r[j][0]
} else {
return r[i][1] > r[j][1]
}
})
return
}
func GetSkyline(buildings [][]int) [][]int {
return getSkyline(buildings)
}
type PriorityQueue struct {
innerPq InnerPq
}
func NewPriorityQueue() PriorityQueue {
iPQ := &InnerPq{}
heap.Init(iPQ)
return PriorityQueue{innerPq: *iPQ}
}
func (pq *PriorityQueue) Push(x int) {
heap.Push(&pq.innerPq, x)
}
func (pq *PriorityQueue) Pop() int {
return heap.Pop(&pq.innerPq).(int)
}
func (pq *PriorityQueue) Len() int {
return pq.innerPq.Len()
}
func (pq *PriorityQueue) Peek() int {
return (pq.innerPq)[0]
}
func (pq *PriorityQueue) Remove(x int) {
pq.innerPq.Remove(x)
}
func (pq *PriorityQueue) RemoveOnce(x int) {
pq.innerPq.RemoveOnce(x)
}
type InnerPq []int
func (ipq InnerPq) Len() int { return len(ipq) }
func (ipq InnerPq) Less(i, j int) bool { return ipq[i] > ipq[j] }
func (ipq InnerPq) Swap(i, j int) { ipq[i], ipq[j] = ipq[j], ipq[i] }
func (ipq *InnerPq) Push(x interface{}) {
*ipq = append(*ipq, x.(int))
}
func (ipq *InnerPq) Pop() interface{} {
old := *ipq
n := len(old)
x := old[n-1]
*ipq = old[0 : n-1]
return x
}
func (ipq *InnerPq) Remove(toRemove interface{}) {
l := ipq.Len()
for i := 0; i < l; i++ {
n := (*ipq)[i]
if n == toRemove {
(*ipq)[i], (*ipq)[l-1] = (*ipq)[l-1], (*ipq)[i]
(*ipq) = (*ipq)[:l-1]
i -= 1
l -= 1
}
}
heap.Init(ipq)
}
func (ipq *InnerPq) RemoveOnce(toRemove interface{}) {
l := ipq.Len()
for i := 0; i < l; i++ {
n := (*ipq)[i]
if n == toRemove {
(*ipq)[i], (*ipq)[l-1] = (*ipq)[l-1], (*ipq)[i]
(*ipq) = (*ipq)[:l-1]
heap.Init(ipq)
return
}
}
}