[Programmers] Lv.2 다리를 지나는 트럭 (Go)

https://school.programmers.co.kr/learn/courses/30/lessons/42583

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문제 설명

트럭 여러 대가 강을 가로지르는 일차선 다리를 정해진 순으로 건너려 합니다. 모든 트럭이 다리를 건너려면 최소 몇 초가 걸리는지 알아내야 합니다. 다리에는 트럭이 최대 bridge_length대 올라갈 수 있으며, 다리는 weight 이하까지의 무게를 견딜 수 있습니다. 단, 다리에 완전히 오르지 않은 트럭의 무게는 무시합니다.

예를 들어, 트럭 2대가 올라갈 수 있고 무게를 10kg까지 견디는 다리가 있습니다. 무게가 [7, 4, 5, 6]kg인 트럭이 순서대로 최단 시간 안에 다리를 건너려면 다음과 같이 건너야 합니다.

따라서, 모든 트럭이 다리를 지나려면 최소 8초가 걸립니다.

solution 함수의 매개변수로 다리에 올라갈 수 있는 트럭 수 bridge_length, 다리가 견딜 수 있는 무게 weight, 트럭 별 무게 truck_weights가 주어집니다. 이때 모든 트럭이 다리를 건너려면 최소 몇 초가 걸리는지 return 하도록 solution 함수를 완성하세요.

 

제한 조건

• bridge_length는 1 이상 10,000 이하입니다.
• weight는 1 이상 10,000 이하입니다.
• truck_weights의 길이는 1 이상 10,000 이하입니다.
• 모든 트럭의 무게는 1 이상 weight 이하입니다.

---

Solution

func solution(bridgeLength int, weight int, truckWeights []int) int {
	
    var result int
	var truckCount = len(truckWeights)
	var passingTrucks = make([]int, bridgeLength)
	var passedTrucks []int

	for {

		result++

		if sumTruckWeight(passingTrucks) == 0 {
			passingTrucks = climbTheBridge(passingTrucks, truckWeights[0])
			truckWeights = passTruck(truckWeights)
			continue
		}

		//한칸진행
		passingTrucks, passedTrucks = crossingTheBridge(passingTrucks, passedTrucks, bridgeLength)

		if passingTrucks[0] == 0 && len(truckWeights) > 0 {
			if sumTruckWeight(passingTrucks)+truckWeights[0] <= weight {
				passingTrucks = climbTheBridge(passingTrucks, truckWeights[0])
				truckWeights = passTruck(truckWeights)
			}
		}

		if len(passedTrucks) == truckCount {
			return result
		}
	}

}

func climbTheBridge(passingTrucks []int, truck int) []int {

	var idx = 0

	for i, p := range passingTrucks {
		if p == 0 {
			idx = i
			break
		}
	}

	passingTrucks[idx] = truck

	return passingTrucks
}

func crossingTheBridge(passingTrucks, passedTrucks []int, bridgeLength int) ([]int, []int) {

	var result = make([]int, bridgeLength)

	for i, p := range passingTrucks {

		if p == 0 {
			continue
		}

		//끝에 도달하면 넘어가기
		if i == len(passingTrucks)-1 {
			passedTrucks = append(passedTrucks, p)
			continue
		}

		result[i+1] = p
	}

	return result, passedTrucks

}

func passTruck(truck []int) []int {

	if len(truck) == 0 {
		return []int{}
	}

	return truck[1:]
}

func sumTruckWeight(passingTrucks []int) int {

	var result int

	for _, p := range passingTrucks {
		result += p
	}

	return result

}