Maximum in Sliding Windows

1. Problem Description

Given an array and a sliding-window size, find the maximum value in every sliding window. For example, for the array {2,3,4,2,6,2,5,1} with window size 3, there are six windows and their maximum values are {4,4,6,6,6,5}. The six windows are: {[2,3,4],2,6,2,5,1}, {2,[3,4,2],6,2,5,1}, {2,3,[4,2,6],2,5,1}, {2,3,4,[2,6,2],5,1}, {2,3,4,2,[6,2,5],1}, {2,3,4,2,6,[2,5,1]}. If the window is larger than the array length, return empty.

2. Approach

• Brute force

3. Implementation

3.1. Brute Force

package main

/**
 *
 * @param num one-dimensional int array
 * @param size int
 * @return one-dimensional int array
 */
func maxInWindows(num []int, size int) []int {
	if size > len(num) || len(num) == 0 || size <= 0 {
		return nil
	}

	res := make([]int, 0)

	for i := 0; i < len(num)-size+1; i++ {
		currentMax := num[i]
		for j := 1; j < size; j++ {
			if num[i+j] > currentMax {
				currentMax = num[i+j]
			}
		}
		res = append(res, currentMax)
	}

	return res
}

4. References

• Sliding Window Maximum - NowCoder