346. Moving Average from Data Stream

346. Moving Average from Data Stream

Question

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

Example:

MovingAverage m = new MovingAverage(3);
m.next(1) = 1
m.next(10) = (1 + 10) / 2
m.next(3) = (1 + 10 + 3) / 3
m.next(5) = (10 + 3 + 5) / 3

Solution

• Method 1: Array ```Java class MovingAverage { private int[] arr; private int size; private int index; /** Initialize your data structure here. */ public MovingAverage(int size) { this.size = size; this.arr = new int[size]; } public double next(int val) { arr[(index++) % this.size] = val; double sum = 0D; for(int v : arr) sum += v; return sum / (index <= size ? index: this.size); } } /**
  • Your MovingAverage object will be instantiated and called as such:
  • MovingAverage obj = new MovingAverage(size);
  • double param_1 = obj.next(val); */ ```
• Method 2: Queue

  class MovingAverage {
      private Queue<Integer> q;
      private int size;
      private double sum;
      /** Initialize your data structure here. */
      public MovingAverage(int size) {
          this.size = size;
          q = new LinkedList<>();
      }
  
      public double next(int val) {
          q.offer(val);
          sum += val;
          while(!q.isEmpty() && q.size() > size){
              sum -= q.poll();
          }
          return sum / q.size();
      }
  }
  
  /**
   * Your MovingAverage object will be instantiated and called as such:
   * MovingAverage obj = new MovingAverage(size);
   * double param_1 = obj.next(val);
   */