_643.java

package com.fishercoder.solutions;

/**
 * 643. Maximum Average Subarray I
 *
 * Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value.
 * And you need to output the maximum average value.

 Example 1:
 Input: [1,12,-5,-6,50,3], k = 4
 Output: 12.75
 Explanation: Maximum average is (12-5-6+50)/4 = 51/4 = 12.75
 Note:
 1 <= k <= n <= 30,000.
 Elements of the given array will be in the range [-10,000, 10,000].
 */
public class _643 {

    public static double findMaxAverage(int[] nums, int k) {
        double sum = 0;
        double maxAve = Integer.MIN_VALUE;
        for (int i = 0; i < nums.length; i++) {
            if (k <= i) {
                sum -= nums[i-k];
            }
            sum += nums[i];
            if ((i+1) >= k) {
                maxAve = Math.max(maxAve, sum / k);
            }
        }
        return maxAve;
    }

    public static void main(String... args) {
//        int[] nums = new int[]{1,12,-5,-6,50,3};
//        int k = 4;

//        int[] nums = new int[]{-1};
//        int k = 1;

        int[] nums = new int[]{-6662,5432,-8558,-8935,8731,-3083,4115,9931,-4006,-3284,-3024,1714,-2825,-2374,-2750,-959,6516,9356,8040,-2169,-9490,-3068,6299,7823,-9767,5751,-7897,6680,-1293,-3486,-6785,6337,-9158,-4183,6240,-2846,-2588,-5458,-9576,-1501,-908,-5477,7596,-8863,-4088,7922,8231,-4928,7636,-3994,-243,-1327,8425,-3468,-4218,-364,4257,5690,1035,6217,8880,4127,-6299,-1831,2854,-4498,-6983,-677,2216,-1938,3348,4099,3591,9076,942,4571,-4200,7271,-6920,-1886,662,7844,3658,-6562,-2106,-296,-3280,8909,-8352,-9413,3513,1352,-8825};
        int k = 90;
        System.out.println(findMaxAverage(nums, k));
    }
}