1656. Design an Ordered Stream.cpp

There are n (id, value) pairs, where id is an integer between 1 and n and value is a string. No two pairs have the same id.

Design a stream that takes the n pairs in an arbitrary order, and returns the values over several calls in increasing order of their ids.

Implement the OrderedStream class:

OrderedStream(int n) Constructs the stream to take n values and sets a current ptr to 1.
String[] insert(int id, String value) Stores the new (id, value) pair in the stream. After storing the pair:
If the stream has stored a pair with id = ptr, then find the longest contiguous incrementing sequence of ids starting with id = ptr and return a list of the values associated with those ids in order. Then, update ptr to the last id + 1.
Otherwise, return an empty list.


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
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"].


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.







class OrderedStream {
public:
    vector<string> v;
    int ptr=1;

    OrderedStream(int n) {
        v.resize(n+1, "");
    }

    vector<string> insert(int id, string value) {
        v[id]=value;
        vector<string> res;

        if(id!=ptr) return res;

        int i=ptr;

        while(i && i<v.size()){
            if(v[i]!="") {
                res.push_back(v[i]);
                i++;
                ptr=i;
            } else break;

        }

        return res;
    }
};

/**
 * Your OrderedStream object will be instantiated and called as such:
 * OrderedStream* obj = new OrderedStream(n);
 * vector<string> param_1 = obj->insert(id,value);
 */