LeetCode-in-All
239. Sliding Window Maximum
Hard
You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.
Return the max sliding window.
Example 1:
Input: nums = [1,3,-1,-3,5,3,6,7], k = 3
Output: [3,3,5,5,6,7]
Explanation:
Window position Max
[1 3 -1] -3 5 3 6 7 3
1 [3 -1 -3] 5 3 6 7 3
1 3 [-1 -3 5] 3 6 7 5
1 3 -1 [-3 5 3] 6 7 5
1 3 -1 -3 [5 3 6] 7 6
1 3 -1 -3 5 [3 6 7] 7
Example 2:
Input: nums = [1], k = 1
Output: [1]
Constraints:
1 <= nums.length <= 105-104 <= nums[i] <= 1041 <= k <= nums.length
Solution
import 'dart:collection';
class Solution {
List<int> maxSlidingWindow(List<int> nums, int k) {
int n = nums.length;
List<int> res = List.filled(n - k + 1, 0);
int x = 0;
Queue<int> dq = Queue();
int i = 0;
int j = 0;
while (j < nums.length) {
// Remove elements from the deque that are smaller than the current element
while (dq.isNotEmpty && dq.last < nums[j]) {
dq.removeLast();
}
// Add the current element to the deque
dq.addLast(nums[j]);
// When the window size reaches k
if (j - i + 1 == k) {
// The element at the front of the deque is the largest in the current window
res[x] = dq.first;
x++;
// If the element at the front of the deque is going out of the window, remove it
if (dq.first == nums[i]) {
dq.removeFirst();
}
// Slide the window to the right
i++;
}
j++;
}
return res;
}
}