三刷239

Author: diguage

docs/0239-sliding-window-maximum.adoc

@@ -1,33 +1,44 @@
 [#0239-sliding-window-maximum]
-= 239. Sliding Window Maximum
+= 239. 滑动窗口最大值
 
-{leetcode}/problems/sliding-window-maximum/[LeetCode - Sliding Window Maximum^]
+https://leetcode.cn/problems/sliding-window-maximum/[LeetCode - 239. 滑动窗口最大值 ^]
 
-Given an array `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.
+给你一个整数数组 `nums`，有一个大小为 `k` 的滑动窗口从数组的最左侧移动到数组的最右侧。你只可以看到在滑动窗口内的 `k` 个数字。滑动窗口每次只向右移动一位。
 
-.Example:
-----
-Input: nums = [1,3,-1,-3,5,3,6,7], and k = 3
-Output: [3,3,5,5,6,7]
-Explanation:
+返回 _滑动窗口中的最大值_ 。
+
+*示例 1：*
 
-Window position                Max
+....
+输入：nums = [1,3,-1,-3,5,3,6,7], k = 3
+输出：[3,3,5,5,6,7]
+解释：
+滑动窗口的位置                最大值
 ---------------               -----
 [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
-----
+....
+
+*示例 2：*
 
-*Note:*
+....
+输入：nums = [1], k = 1
+输出：[1]
+....
 
-You may assume `k` is always valid, `1 ≤ k ≤` input array's size for non-empty array.
 
-*Follow up:*
+*提示：*
 
-Could you solve it in linear time?
+* `1 \<= nums.length \<= 10^5^`
+* `-10^4^ \<= nums[i] \<= 10^4^`
+* `+1 <= k <= nums.length+`
+
+
+====
 
 == 思路分析
 
@@ -87,6 +98,15 @@ include::{sourcedir}/_0239_SlidingWindowMaximum.java[tag=answer]
 include::{sourcedir}/_0239_SlidingWindowMaximum_2.java[tag=answer]
 ----
 --
+
+三刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0239_SlidingWindowMaximum_3.java[tag=answer]
+----
+--
 ====
 
 == 思考题

logbook/202503.adoc

@@ -568,6 +568,10 @@ endif::[]
 |{doc_base_url}/0224-basic-calculator.adoc[题解]
 |❌ 使用双栈来分别存放数字和操作符。
 
+|{counter:codes2503}
+|{leetcode_base_url}/sliding-window-maximum/[239. Sliding Window Maximum^]
+|{doc_base_url}/0239-sliding-window-maximum.adoc[题解]
+|✅ 单调栈。有很多细节需要考虑。
 
 |===
 

src/main/java/com/diguage/algo/leetcode/_0239_SlidingWindowMaximum_3.java

@@ -0,0 +1,31 @@
+package com.diguage.algo.leetcode;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+public class _0239_SlidingWindowMaximum_3 {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-05-01 08:09:17
+   */
+  public int[] maxSlidingWindow(int[] nums, int k) {
+    Deque<Integer> stack = new ArrayDeque<>(k + 1);
+    int[] result = new int[nums.length - k + 1];
+    for (int i = 0; i < nums.length; i++) {
+      while (!stack.isEmpty() && nums[stack.peekLast()] <= nums[i]) {
+        stack.pollLast();
+      }
+      stack.offerLast(i);
+      if (stack.peekFirst() <= i - k) {
+        stack.pollFirst();
+      }
+      if (i >= k - 1) {
+        result[i - k + 1] = nums[stack.peekFirst()];
+      }
+    }
+    return result;
+  }
+  // end::answer[]
+}