Lintcode 642. Moving Average from Data Stream

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

Example

Example 1:

MovingAverage m = new MovingAverage(3);
m.next(1) = 1 // return 1.00000
m.next(10) = (1 + 10) / 2 // return 5.50000
m.next(3) = (1 + 10 + 3) / 3 // return 4.66667
m.next(5) = (10 + 3 + 5) / 3 // return 6.00000

Code (Java):

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public class MovingAverage {     /*     * @param size: An integer     */     private Deque<Integer> nums;     private long sum;     private int windowSize;     public MovingAverage(int size) {         // do intialization if necessary         this.nums = new LinkedList<>();         this.sum = 0;         this.windowSize = size;     }       /*      * @param val: An integer      * @return:       */     public double next(int val) {         // write your code here         sum += val;         nums.addLast(val);         if (nums.size() > windowSize) {             int headVal = nums.removeFirst();             sum -= headVal;         }           return (double) sum / nums.size();     } }