feat: add solutions to lc problem: No.0239.Sliding Window Maximum

hikary · Aug 18, 2021 · ce05895 · ce05895
1 parent c3386dc
commit ce05895
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diff --git a/lcof/面试题59 - I. 滑动窗口的最大值/README.md b/lcof/面试题59 - I. 滑动窗口的最大值/README.md
@@ -33,7 +33,20 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
-双端队列实现。
+单调队列。
+
+单调队列常见模型：找出滑动窗口中的最大值/最小值。模板：
+
+```python
+q = deque()
+for i in range(n):
+    # 判断队头是否滑出窗口
+    while q and checkout_out(q[0]):
+        q.popleft()
+    while q and check(q[-1]):
+        q.pop()
+    q.append(i)
+```
 
 <!-- tabs:start -->
 
@@ -44,14 +57,13 @@
 ```python
 class Solution:
     def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
-        q, res = [], []
+        q, res = collections.deque(), []
         for i, num in enumerate(nums):
-            while len(q) != 0 and nums[q[-1]] <= num:
-                q.pop(-1)
+            if q and i - k + 1 > q[0]:
+                q.popleft()
+            while q and nums[q[-1]] <= num:
+                q.pop()
             q.append(i)
-
-            if q[0] == i - k:
-                q = q[1:]
             if i >= k - 1:
                 res.append(nums[q[0]])
         return res

diff --git a/lcof/面试题59 - I. 滑动窗口的最大值/Solution.java b/lcof/面试题59 - I. 滑动窗口的最大值/Solution.java
@@ -1,21 +1,21 @@
 class Solution {
     public int[] maxSlidingWindow(int[] nums, int k) {
-        int index = 0, n = nums.length;
-        if (k == 0 || n == 0) {
+        int n = nums.length;
+        if (n == 0) {
             return new int[0];
         }
         int[] res = new int[n - k + 1];
-        LinkedList<Integer> q = new LinkedList<>();
-        for (int i = 0; i < n; ++i) {
+        Deque<Integer> q = new LinkedList<>();
+        for (int i = 0, j = 0; i < n; ++i) {
+            if (!q.isEmpty() && i - k + 1 > q.peekFirst()) {
+                q.pollFirst();
+            }
             while (!q.isEmpty() && nums[q.peekLast()] <= nums[i]) {
                 q.pollLast();
             }
-            q.addLast(i);
-            if (q.peekFirst() == i - k) {
-                q.pollFirst();
-            }
+            q.offerLast(i);
             if (i >= k - 1) {
-                res[index++] = nums[q.peekFirst()];
+                res[j++] = nums[q.peekFirst()];
             }
         }
         return res;

diff --git a/lcof/面试题59 - I. 滑动窗口的最大值/Solution.py b/lcof/面试题59 - I. 滑动窗口的最大值/Solution.py
@@ -1,13 +1,12 @@
 class Solution:
     def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
-        q, res = [], []
+        q, res = collections.deque(), []
         for i, num in enumerate(nums):
-            while len(q) != 0 and nums[q[-1]] <= num:
-                q.pop(-1)
+            if q and i - k + 1 > q[0]:
+                q.popleft()
+            while q and nums[q[-1]] <= num:
+                q.pop()
             q.append(i)
-
-            if q[0] == i - k:
-                q = q[1:]
             if i >= k - 1:
                 res.append(nums[q[0]])
         return res
diff --git a/solution/0200-0299/0239.Sliding Window Maximum/README.md b/solution/0200-0299/0239.Sliding Window Maximum/README.md
@@ -70,22 +70,70 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+单调队列。
+
+单调队列常见模型：找出滑动窗口中的最大值/最小值。模板：
+
+```python
+q = deque()
+for i in range(n):
+    # 判断队头是否滑出窗口
+    while q and checkout_out(q[0]):
+        q.popleft()
+    while q and check(q[-1]):
+        q.pop()
+    q.append(i)
+```
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
+        q, res = collections.deque(), []
+        for i, num in enumerate(nums):
+            if q and i - k + 1 > q[0]:
+                q.popleft()
+            while q and nums[q[-1]] <= num:
+                q.pop()
+            q.append(i)
+            if i >= k - 1:
+                res.append(nums[q[0]])
+        return res
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public int[] maxSlidingWindow(int[] nums, int k) {
+        int n = nums.length;
+        if (n == 0) {
+            return new int[0];
+        }
+        int[] res = new int[n - k + 1];
+        Deque<Integer> q = new LinkedList<>();
+        for (int i = 0, j = 0; i < n; ++i) {
+            if (!q.isEmpty() && i - k + 1 > q.peekFirst()) {
+                q.pollFirst();
+            }
+            while (!q.isEmpty() && nums[q.peekLast()] <= nums[i]) {
+                q.pollLast();
+            }
+            q.offerLast(i);
+            if (i >= k - 1) {
+                res[j++] = nums[q.peekFirst()];
+            }
+        }
+        return res;
+    }
+}
 ```
 
 ### **JavaScript**
@@ -118,6 +166,51 @@ var maxSlidingWindow = function (nums, k) {
 };
 ```
 
+### **C++**
+
+```cpp
+class Solution {
+public:
+	vector<int> maxSlidingWindow(vector<int> &nums, int k) {
+		vector<int> res;
+		deque<int> q;
+		for (int i = 0; i < nums.size(); ++i)
+		{
+			if (!q.empty() && i - k + 1 > q.front())
+				q.pop_front();
+			while (!q.empty() && nums[q.back()] <= nums[i])
+				q.pop_back();
+			q.push_back(i);
+			if (i >= k - 1)
+				res.push_back(nums[q.front()]);
+		}
+		return res;
+	}
+};
+```
+
+### **Go**
+
+```go
+func maxSlidingWindow(nums []int, k int) []int {
+	var res []int
+	var q []int
+	for i, num := range nums {
+		if len(q) > 0 && i-k+1 > q[0] {
+			q = q[1:]
+		}
+		for len(q) > 0 && nums[q[len(q)-1]] <= num {
+			q = q[:len(q)-1]
+		}
+		q = append(q, i)
+		if i >= k-1 {
+			res = append(res, nums[q[0]])
+		}
+	}
+	return res
+}
+```
+
 ### **...**
 
 ```

diff --git a/solution/0200-0299/0239.Sliding Window Maximum/README_EN.md b/solution/0200-0299/0239.Sliding Window Maximum/README_EN.md
@@ -70,13 +70,46 @@ Window position                Max
 ### **Python3**
 
 ```python
-
+class Solution:
+    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
+        q, res = collections.deque(), []
+        for i, num in enumerate(nums):
+            if q and i - k + 1 > q[0]:
+                q.popleft()
+            while q and nums[q[-1]] <= num:
+                q.pop()
+            q.append(i)
+            if i >= k - 1:
+                res.append(nums[q[0]])
+        return res
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public int[] maxSlidingWindow(int[] nums, int k) {
+        int n = nums.length;
+        if (n == 0) {
+            return new int[0];
+        }
+        int[] res = new int[n - k + 1];
+        Deque<Integer> q = new LinkedList<>();
+        for (int i = 0, j = 0; i < n; ++i) {
+            if (!q.isEmpty() && i - k + 1 > q.peekFirst()) {
+                q.pollFirst();
+            }
+            while (!q.isEmpty() && nums[q.peekLast()] <= nums[i]) {
+                q.pollLast();
+            }
+            q.offerLast(i);
+            if (i >= k - 1) {
+                res[j++] = nums[q.peekFirst()];
+            }
+        }
+        return res;
+    }
+}
 ```
 
 ### **JavaScript**
@@ -109,6 +142,51 @@ var maxSlidingWindow = function (nums, k) {
 };
 ```
 
+### **C++**
+
+```cpp
+class Solution {
+public:
+	vector<int> maxSlidingWindow(vector<int> &nums, int k) {
+		vector<int> res;
+		deque<int> q;
+		for (int i = 0; i < nums.size(); ++i)
+		{
+			if (!q.empty() && i - k + 1 > q.front())
+				q.pop_front();
+			while (!q.empty() && nums[q.back()] <= nums[i])
+				q.pop_back();
+			q.push_back(i);
+			if (i >= k - 1)
+				res.push_back(nums[q.front()]);
+		}
+		return res;
+	}
+};
+```
+
+### **Go**
+
+```go
+func maxSlidingWindow(nums []int, k int) []int {
+	var res []int
+	var q []int
+	for i, num := range nums {
+		if len(q) > 0 && i-k+1 > q[0] {
+			q = q[1:]
+		}
+		for len(q) > 0 && nums[q[len(q)-1]] <= num {
+			q = q[:len(q)-1]
+		}
+		q = append(q, i)
+		if i >= k-1 {
+			res = append(res, nums[q[0]])
+		}
+	}
+	return res
+}
+```
+
 ### **...**
 
 ```

diff --git a/solution/0200-0299/0239.Sliding Window Maximum/Solution.cpp b/solution/0200-0299/0239.Sliding Window Maximum/Solution.cpp
@@ -0,0 +1,18 @@
+class Solution {
+public:
+	vector<int> maxSlidingWindow(vector<int> &nums, int k) {
+		vector<int> res;
+		deque<int> q;
+		for (int i = 0; i < nums.size(); ++i)
+		{
+			if (!q.empty() && i - k + 1 > q.front())
+				q.pop_front();
+			while (!q.empty() && nums[q.back()] <= nums[i])
+				q.pop_back();
+			q.push_back(i);
+			if (i >= k - 1)
+				res.push_back(nums[q.front()]);
+		}
+		return res;
+	}
+};
diff --git a/solution/0200-0299/0239.Sliding Window Maximum/Solution.go b/solution/0200-0299/0239.Sliding Window Maximum/Solution.go
@@ -0,0 +1,17 @@
+func maxSlidingWindow(nums []int, k int) []int {
+	var res []int
+	var q []int
+	for i, num := range nums {
+		if len(q) > 0 && i-k+1 > q[0] {
+			q = q[1:]
+		}
+		for len(q) > 0 && nums[q[len(q)-1]] <= num {
+			q = q[:len(q)-1]
+		}
+		q = append(q, i)
+		if i >= k-1 {
+			res = append(res, nums[q[0]])
+		}
+	}
+	return res
+}
diff --git a/solution/0200-0299/0239.Sliding Window Maximum/Solution.java b/solution/0200-0299/0239.Sliding Window Maximum/Solution.java
@@ -1,23 +1,23 @@
 class Solution {
     public int[] maxSlidingWindow(int[] nums, int k) {
-        if (nums == null || nums.length == 0 || k <= 0) {
+        int n = nums.length;
+        if (n == 0) {
             return new int[0];
         }
-        int[] res = new int[nums.length - k + 1];
-        int index = 0;
-        Deque<Integer> q = new ArrayDeque<>(k);
-        for (int i = 0; i < nums.length; ++i) {
-            while (!q.isEmpty() && nums[i] >= nums[q.peekLast()]) {
+        int[] res = new int[n - k + 1];
+        Deque<Integer> q = new LinkedList<>();
+        for (int i = 0, j = 0; i < n; ++i) {
+            if (!q.isEmpty() && i - k + 1 > q.peekFirst()) {
+                q.pollFirst();
+            }
+            while (!q.isEmpty() && nums[q.peekLast()] <= nums[i]) {
                 q.pollLast();
             }
             q.offerLast(i);
-            if (i - q.peekFirst() >= k) {
-                q.pollFirst();
-            }
             if (i >= k - 1) {
-                res[index++] = nums[q.peekFirst()];
+                res[j++] = nums[q.peekFirst()];
             }
         }
         return res;
     }
-}
+}