滑雪题

// test case 1
var travel = [["start","3","A"],["A","6","B"],["B","5","END"]]
var point = ["A":10,"B": 10,"C":10,"END" : 10]

func getMaxScore(_ travel: [[String]], _ reward : [String: Int]) -> Int{
    var map = [String: [String: Int]]()   // from : [to, cost]
    var indegree = [String: Int]()
    var maxScore = [String: Int]()
    print(map)
    var queue = [String]()
    queue.append("start")

    for trip in travel{
        let from = trip[0]
        let to = trip[2]
        let cost = Int(trip[1])!
        indegree[to, default: 0] += 1
        if indegree[from] == nil {
            indegree[from] = 0
        }
        map[from, default: [String:Int]()][to] = cost
    }
    print(map)
    var visited = [String]()
    visited.append("start")

    maxScore["start"] = 0
    var res = 0
    while queue.count > 0 {
        let cur = queue.removeFirst()

        if let toMap = map[cur]{
            for (to, cost) in toMap{
                indegree[to] = indegree[to]! - 1
                if indegree[to] == 0{
                    queue.append(to)
                }

                if let score = maxScore[to]{
                    maxScore[to] = max(score, maxScore[cur]! + reward[to]! - cost)
                }else{
                    print(cur)
                    print(maxScore)
                    maxScore[to] = maxScore[cur]! +  reward[to]! - cost

                }
                if to == "END"{
                    res = max(maxScore[to]!, res)
                }

            }
        }
    }
    return res
}


let res = getMaxScore(travel, point)
print(res)