package top100liked

import (
	"fmt"
	"testing"
)

// https://leetcode.cn/problems/sliding-window-maximum/?envType=study-plan-v2&envId=top-100-liked

func maxSlidingWindow(nums []int, k int) []int {
	if len(nums) == 0 || k == 0 {
		return []int{}
	}

	deque := make([]int, 0) // 存下标，单调递减（对应值）
	result := make([]int, 0, len(nums)-k+1)

	for i := 0; i < len(nums); i++ {
		// 1. 从队尾移除所有 <= nums[i] 的下标
		for len(deque) > 0 && nums[deque[len(deque)-1]] <= nums[i] {
			deque = deque[:len(deque)-1]
		}
		// 2. 加入当前下标
		deque = append(deque, i)
		// 3. 如果队首下标已出窗口，移除
		if deque[0] < i-k+1 {
			deque = deque[1:]
		}
		// 4. 窗口形成后，记录最大值
		if i >= k-1 {
			result = append(result, nums[deque[0]])
		}
	}
	return result
}

func TestS11(t *testing.T) {
	fmt.Printf("%+v", maxSlidingWindow([]int{1, 3, -1, -3, 5, 3, 6, 7}, 3))
	fmt.Printf("%+v", maxSlidingWindow([]int{1}, 1))
	fmt.Printf("%+v", maxSlidingWindow([]int{9, 9, 8, 8, 7, 7, 6, 6}, 2))
	fmt.Printf("%+v", maxSlidingWindow([]int{10, 9, 8, 7, 6, 5}, 3))
}