59 lines
1.7 KiB
Kotlin
59 lines
1.7 KiB
Kotlin
import java.util.PriorityQueue
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class Solution {
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fun minRefuelStops(target: Int, startFuel: Int, stations: Array<IntArray>): Int {
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var maxReach = startFuel
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val availableRefuelling = PriorityQueue<Int>(reverseOrder())
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var refuelled = 0
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var i = 0
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while (maxReach < target) {
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while (i < stations.size && stations[i][0] <= maxReach) {
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// keep track of possible refuels
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availableRefuelling.add(stations[i][1])
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i++
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}
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if (availableRefuelling.isEmpty()) {
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// no refuels are available and target has not been reached
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return -1
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}
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// refuel at least once in order to progress
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maxReach += availableRefuelling.poll()!!
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refuelled++
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}
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return refuelled
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}
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}
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fun main() {
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val s = Solution()
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check(s.minRefuelStops(1, 1, arrayOf()) == 0)
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check(s.minRefuelStops(100, 1, arrayOf(intArrayOf(10, 100))) == -1)
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check(
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s.minRefuelStops(
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100, 10, arrayOf(intArrayOf(10, 60), intArrayOf(20, 30), intArrayOf(30, 30), intArrayOf(60, 40))
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) == 2
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)
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check(
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s.minRefuelStops(
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1000, 299,
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arrayOf(
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intArrayOf(13, 21),
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intArrayOf(26, 115),
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intArrayOf(100, 47),
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intArrayOf(225, 99),
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intArrayOf(299, 141),
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intArrayOf(444, 198),
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intArrayOf(608, 190),
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intArrayOf(636, 157),
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intArrayOf(647, 255),
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intArrayOf(841, 123)
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)
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) == 4
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)
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}
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