1656. Design an Ordered Stream

Description

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.

Solutions

Solution 1

Python Code
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class OrderedStream:
    def __init__(self, n: int):
        self.data = [None] * n
        self.ptr = 0

    def insert(self, idKey: int, value: str) -> List[str]:
        self.data[idKey - 1] = value
        ans = []
        while self.ptr < len(self.data) and self.data[self.ptr]:
            ans.append(self.data[self.ptr])
            self.ptr += 1
        return ans


# Your OrderedStream object will be instantiated and called as such:
# obj = OrderedStream(n)
# param_1 = obj.insert(idKey,value)

Java Code
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class OrderedStream {
    private String[] data;
    private int ptr;

    public OrderedStream(int n) {
        data = new String[n];
        ptr = 0;
    }

    public List<String> insert(int idKey, String value) {
        data[idKey - 1] = value;
        List<String> ans = new ArrayList<>();
        while (ptr < data.length && data[ptr] != null) {
            ans.add(data[ptr++]);
        }
        return ans;
    }
}

/**
 * Your OrderedStream object will be instantiated and called as such:
 * OrderedStream obj = new OrderedStream(n);
 * List<String> param_1 = obj.insert(idKey,value);
 */

C++ Code
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class OrderedStream {
public:
    vector<string> data;
    int ptr = 0;

    OrderedStream(int n) {
        data.resize(n, "");
    }

    vector<string> insert(int idKey, string value) {
        data[idKey - 1] = value;
        vector<string> ans;
        while (ptr < data.size() && data[ptr] != "") ans.push_back(data[ptr++]);
        return ans;
    }
};

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

Go Code
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type OrderedStream struct {
	data []string
	ptr  int
}

func Constructor(n int) OrderedStream {
	data := make([]string, n)
	return OrderedStream{data, 0}
}

func (this *OrderedStream) Insert(idKey int, value string) []string {
	this.data[idKey-1] = value
	var ans []string
	for this.ptr < len(this.data) && this.data[this.ptr] != "" {
		ans = append(ans, this.data[this.ptr])
		this.ptr++
	}
	return ans
}

/**
 * Your OrderedStream object will be instantiated and called as such:
 * obj := Constructor(n);
 * param_1 := obj.Insert(idKey,value);
 */

TypeScript Code
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class OrderedStream {
    private ptr: number;
    private vals: string[];

    constructor(n: number) {
        this.ptr = 0;
        this.vals = new Array(n);
    }

    insert(idKey: number, value: string): string[] {
        this.vals[idKey - 1] = value;
        const res = [];
        while (this.vals[this.ptr] != null) {
            res.push(this.vals[this.ptr]);
            this.ptr++;
        }
        return res;
    }
}

/**
 * Your OrderedStream object will be instantiated and called as such:
 * var obj = new OrderedStream(n)
 * var param_1 = obj.insert(idKey,value)
 */

Rust Code
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struct OrderedStream {
    ptr: usize,
    vals: Vec<Option<String>>,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl OrderedStream {
    fn new(n: i32) -> Self {
        Self { ptr: 0, vals: vec![None; n as usize] }
    }

    fn insert(&mut self, id_key: i32, value: String) -> Vec<String> {
        self.vals[(id_key - 1) as usize] = Some(value);
        let mut res = Vec::new();
        while self.ptr < self.vals.len() {
            if let Some(s) = &self.vals[self.ptr] {
                res.push(s.clone());
                self.ptr += 1;
            } else {
                break;
            }
        }
        res
    }
}/**
 * Your OrderedStream object will be instantiated and called as such:
 * let obj = OrderedStream::new(n);
 * let ret_1: Vec<String> = obj.insert(idKey, value);
 */