LeetCode in Kotlin

1656. Design an Ordered Stream

Easy

There is a stream of n (idKey, value) pairs arriving in an arbitrary order, where idKey is an integer between 1 and n and value is a string. No two pairs have the same id.

Design a stream that returns the values in increasing order of their IDs by returning a chunk (list) of values after each insertion. The concatenation of all the chunks should result in a list of the sorted values.

Implement the OrderedStream class:

• OrderedStream(int n) Constructs the stream to take n values.
• String[] insert(int idKey, String value) Inserts the pair (idKey, value) into the stream, then returns the largest possible chunk of currently inserted values that appear next in the order.

Example:

Input [“OrderedStream”, “insert”, “insert”, “insert”, “insert”, “insert”]

[[5], [3, “ccccc”], [1, “aaaaa”], [2, “bbbbb”], [5, “eeeee”], [4, “ddddd”]]

Output: [null, [], [“aaaaa”], [“bbbbb”, “ccccc”], [], [“ddddd”, “eeeee”]]

Explanation:

// Note that the values ordered by ID is ["aaaaa", "bbbbb", "ccccc", "ddddd", "eeeee"].
OrderedStream os = new OrderedStream(5);
os.insert(3, "ccccc"); // Inserts (3, "ccccc"), returns [].
os.insert(1, "aaaaa"); // Inserts (1, "aaaaa"), returns ["aaaaa"].
os.insert(2, "bbbbb"); // Inserts (2, "bbbbb"), returns ["bbbbb", "ccccc"].
os.insert(5, "eeeee"); // Inserts (5, "eeeee"), returns [].
os.insert(4, "ddddd"); // Inserts (4, "ddddd"), returns ["ddddd", "eeeee"].
// Concatentating all the chunks returned:
// [] + ["aaaaa"] + ["bbbbb", "ccccc"] + [] + ["ddddd", "eeeee"] = ["aaaaa", "bbbbb", "ccccc", "ddddd", "eeeee"]
// The resulting order is the same as the order above. 

Constraints:

• 1 <= n <= 1000
• 1 <= id <= n
• value.length == 5
• value consists only of lowercase letters.
• Each call to insert will have a unique id.
• Exactly n calls will be made to insert.

Solution

class OrderedStream(n: Int) {
    private val str: Array<String?>
    private var ptr = 0

    init {
        str = arrayOfNulls(n)
    }

    fun insert(idKey: Int, value: String?): List<String?> {
        str[idKey - 1] = value
        val list: MutableList<String?> = ArrayList()
        while (ptr < str.size && str[ptr] != null) {
            list.add(str[ptr])
            ptr++
        }
        return list
    }
}
/*
 * Your OrderedStream object will be instantiated and called as such:
 * var obj = OrderedStream(n)
 * var param_1 = obj.insert(idKey,value)
 */

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