Moving Average from Data Stream

Problem

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

Implement the MovingAverage class:

• MovingAverage(int size) Initializes the object with the size of the window size.
• double next(int val) Returns the moving average of the last size values of the stream.

Constraints

• 1 <= size <= 1000
• -105 <= val <= 105
• At most 104 calls will be made to next.

Solution

The problem Moving Average from Data Stream can be solved by implementing a cache using queue to keep track of integers within a window size.

Implementation

class MovingAverage
{
  private:
    int capacity;
    double sum;
    queue<int> cache;

  public:
    MovingAverage(int size)
    {
        capacity = size;
        sum = 0;
    }

    double next(int val)
    {
        if (cache.size() == capacity)
        {
            sum -= cache.front();
            cache.pop();
        }

        sum += val;
        cache.push(val);

        return sum / cache.size();
    }
};

/**
 * Your MovingAverage object will be instantiated and called as such:
 * MovingAverage* obj = new MovingAverage(size);
 * double param_1 = obj->next(val);
 */