Maximum Average Subarray

Given an array with positive and negative numbers, find the maximum average subarray which length should be greater or equal to given length k.

Example

Given nums = [1, 12, -5, -6, 50, 3], k = 3

Return 15.667 // (-6 + 50 + 3) / 3 = 15.667

利用队列建立窗口

 public class Solution {
     /**
      * @param nums an array with positive and negative numbers
      * @param k an integer
      * @return the maximum average
      */
     public double maxAverage(int[] nums, int k) {
         // Write your code here
         if(k<=0||nums==null||nums.length==0) return 0;
         double average = Double.NEGATIVE_INFINITY;
         double sum = 0;
         Queue<Integer> queue = new LinkedList<Integer>();

         for(int i=0;i< nums.length;i++){
             if(i>=k){
                 int out = queue.poll();
                 sum-=out;
             }
             queue.offer(nums[i]);
             sum+=nums[i];
             if(i>=k-1){
                 average = Math.max(average, sum/k);
             }
         }

         return average;
     }
 }