Problem
For a stream of integers, implement a data structure that checks if the last k integers parsed in the stream are equal to value.
Implement the DataStream class:
DataStream(int value, int k)Initializes the object with an empty integer stream and the two integersvalueandk.boolean consec(int num)Addsnumto the stream of integers. Returnstrueif the lastkintegers are equal tovalue, andfalseotherwise. If there are less thankintegers, the condition does not hold true, so returnsfalse.
Example 1:
Input
["DataStream", "consec", "consec", "consec", "consec"]
[[4, 3], [4], [4], [4], [3]]
Output
[null, false, false, true, false]
Explanation
DataStream dataStream = new DataStream(4, 3); //value = 4, k = 3
dataStream.consec(4); // Only 1 integer is parsed, so returns False.
dataStream.consec(4); // Only 2 integers are parsed.
// Since 2 is less than k, returns False.
dataStream.consec(4); // The 3 integers parsed are all equal to value, so returns True.
dataStream.consec(3); // The last k integers parsed in the stream are [4,4,3].
// Since 3 is not equal to value, it returns False.
Constraints:
1 <= value, num <= 1091 <= k <= 105At most
105calls will be made toconsec.
Solution (Java)
class DataStream {
private int val, k, count;
public DataStream(int value, int k) {
this.val = value;
this.k = k;
this.count = 0;
}
public boolean consec(int num) {
// if num == val, increment the streak else set it to 0
count = (num == val)? count + 1 : 0;
return count >= k;
}
}
/**
* Your DataStream object will be instantiated and called as such:
* DataStream obj = new DataStream(value, k);
* boolean param_1 = obj.consec(num);
*/
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).