Created
January 22, 2016 23:31
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package org.sdo.alg.other | |
/** | |
* Created by dsemenov | |
* Date: 1/7/16. | |
*/ | |
trait WaterCollect { | |
def collectWater(towers: List[Int]): Int = { | |
def walkMax(towers: List[Int]): List[Int] = { | |
var tempMax = 0 | |
towers.map { | |
elem => | |
if (tempMax < elem) { | |
tempMax = elem | |
tempMax | |
} | |
else | |
tempMax | |
} | |
} | |
val lefMax = walkMax(towers) | |
val rigthMax = walkMax(towers.reverse).reverse | |
towers.foldLeft((0, lefMax, rigthMax)) { (context, elem) => | |
context match { | |
case (volume, leftM, rightM) => | |
val left = leftM.head | |
val right = rightM.head | |
val min = math.min(left, right) | |
(volume + min - elem, leftM.tail, rightM.tail) | |
} | |
} _1 | |
} | |
def waterCollect2(towers: List[Int]): Int = towers match { | |
case Nil => 0 | |
case head :: Nil => 0 | |
case head :: tail => | |
val leftTower = head | |
val rightTower = tail.last | |
val waterLevel = math.min(leftTower, rightTower) | |
val water = (towers.length - 2) * waterLevel | |
val (nextTowers, leftOrRight) = if (leftTower < rightTower) (towers.drop(1), Left(leftTower)) else (towers.dropRight(1), Right(rightTower)) | |
water + waterCollectInternal(nextTowers, waterLevel, leftOrRight) | |
} | |
def waterCollectInternal(towers: List[Int], waterLevel: Int, leftOrRight: Either[Int, Int]): Int = towers match { | |
case Nil => 0 | |
case head :: Nil => 0 | |
case head :: tail => | |
val leftTower = head | |
val rightTower = tail.last | |
val newWaterLevel = math.max(math.min(leftTower, rightTower), waterLevel) | |
val currentTowerAdjustment = leftOrRight match { | |
case Left(_) if newWaterLevel < leftTower => -waterLevel | |
case Left(_) => -math.min(leftTower, waterLevel) | |
case Right(_) if newWaterLevel < rightTower => -waterLevel | |
case Right(_) => -math.min(rightTower,waterLevel) | |
} | |
val waterAdjustment = currentTowerAdjustment + (towers.length - 2) * (newWaterLevel - waterLevel) | |
val (nextTowers, newLeftOrRight) = if (leftTower < rightTower) (towers.drop(1), Left(leftTower)) else (towers.dropRight(1), Right(rightTower)) | |
waterAdjustment + waterCollectInternal(nextTowers, newWaterLevel, newLeftOrRight) | |
} | |
} |
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