239. 滑动窗口最大值

test011.cpp

@@ -1,4 +1,4 @@
-// 1.优先队列
+// 方法一、优先队列
 class Solution {
 public:
     vector<int> maxSlidingWindow(vector<int>& nums, int k) {
@@ -19,4 +19,30 @@ public:
     }
 };
 
-// 
+// 方法二、单调队列
+class Solution {
+public:
+    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
+        int n = nums.size();
+        deque<int> q; 
+        vector<int> ans;
+        for(int i = 0; i < k; i++){
+            while(!q.empty() && nums[i] >= nums[q.back()]){
+                q.pop_back();
+            }
+            q.push_back(i);
+        }
+        ans.push_back(nums[q.front()]);
+        for(int i = k; i < n; i++){
+            while(!q.empty() && nums[i] >= nums[q.back()]){
+                q.pop_back();
+            }
+            q.push_back(i);
+            while(q.front() <= i - k){
+                q.pop_front();
+            }
+            ans.push_back(nums[q.front()]);
+        }
+        return ans;
+    }
+};