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0480-sliding-window-median.swift
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0480-sliding-window-median.swift
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class Solution {
func medianSlidingWindow(_ nums: [Int], _ k: Int) -> [Double] {
var lowHeap = Heap<Int>(>)
var highHeap = Heap<Int>(<)
var counts: [Int: Int] = [:]
for i in 0..<k {
lowHeap.insert(nums[i])
}
for _ in 0..<(k / 2) {
highHeap.insert(lowHeap.pop()!)
}
var result = [Double]()
let median: () -> Double = {
if k % 2 == 0 {
return Double(lowHeap.top!) / 2 + Double(highHeap.top!) / 2
} else {
return Double(lowHeap.top!)
}
}
result.append(median())
for i in k..<nums.count {
let old = nums[i - k]
let new = nums[i]
counts[old, default: 0] += 1
var balance = (new <= lowHeap.top! ? -1 : 1) + (old <= lowHeap.top! ? 1 : -1)
new <= lowHeap.top! ? lowHeap.insert(new) : highHeap.insert(new)
if balance > 0 {
lowHeap.insert(highHeap.pop()!)
} else if balance < 0 {
highHeap.insert(lowHeap.pop()!)
}
while !lowHeap.isEmpty && counts[lowHeap.top!, default: 0] > 0 {
counts[lowHeap.top!]! -= 1
lowHeap.pop()
}
while !highHeap.isEmpty && counts[highHeap.top!, default: 0] > 0 {
counts[highHeap.top!]! -= 1
highHeap.pop()
}
result.append(median())
}
return result
}
}