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;
    }
}