题解 | #滑动窗口的最大值#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param num int整型一维数组
     * @param size int整型
     * @return int整型ArrayList
     */
    public ArrayList<Integer> maxInWindows (int[] num, int size) {
        // write code here
        // 比较最后一个元素和当前最大元素的大小，如果大于就存储，小于就存一个当前最大元素
        ArrayList<Integer> res = new ArrayList<>();
        if (size == 0 || num == null || num.length == 0 || num.length < size) {
            return res;
        }
        ArrayList<Integer> stack = new ArrayList<>();
        if (size == 1) {
            for (int i = 0; i < num.length; ++i) {
                res.add(num[i]);
            }
            return res;
        }
        if (num.length == 1) {
            res.add(num[0]);
            return res;
        } else if (num.length == 2) {
            res.add(num[0] > num[1] ? num[0] : num[1]);
            return res;
        } else {
            int maxx = num[0];
            for (int i = 0; i < size; ++i) {
                stack.add(num[i]);
                if (num[i] > maxx) {
                    maxx = num[i];
                }
            }
            // maxx = Math.max(stack.get(2), Math.max(stack.get(0), stack.get(1)));
            res.add(maxx);
            System.out.println(maxx);
            for (int i = size; i < num.length; ++i) {
                stack.add(num[i]);
                stack.remove(0);

                if (stack.contains(maxx)) {
                    if (num[i] > maxx) {
                        maxx = num[i];
                        res.add(num[i]);
                    } else {
                        res.add(maxx);
                    }
                    System.out.println(":" + maxx);
                } else {
                    maxx = Math.max(stack.get(2), Math.max(stack.get(0), stack.get(1)));
                    res.add(maxx);
                }

            }
        }
        return res;
    }
}