05 August 2008
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.
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import java.util.LinkedList;
import java.util.List;
class OrderedStream {
String[] tracker;
int pointer = 0;
public OrderedStream(int n) {
tracker = new String[n];
}
public List<String> insert(int idKey, String value) {
List<String> list = new ArrayList<>();
tracker[idKey - 1] = value;
while (pointer < tracker.length && tracker[pointer] != null) {
list.add(tracker[pointer]);
pointer++;
}
return list;
}
}
/**
* Your OrderedStream object will be instantiated and called as such:
* OrderedStream obj = new OrderedStream(n);
* List<String> param_1 = obj.insert(idKey,value);
*/