class Main { public static int maxSubArray(int[] nums, int k){ int currentSum = 0; //Find sum of first window for(int i=0; i<k; i++){ currentSum= currentSum + nums[i]; } int maxSum= currentSum; //slide window for(int j=k;j<nums.length;j++){ currentSum= currentSum + nums[j] - nums[j-k]; maxSum= Math.max(currentSum, maxSum); } return maxSum; } public static void main(String[] args) { int nums[] = {1,5,4,2,9,9,9}; int k = 3; System.out.println(maxSubArray(nums, k)); } }