Sliding Window Maximum - Leetcode

Fixes codemistic#716

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "C_Cpp.errorSquiggles": "disabled"
+}

CPP/sliding-window/Sliding Window Maximum.cpp

@@ -1,35 +1,87 @@
 class Solution {
 public:
     vector<int> maxSlidingWindow(vector<int>& nums, int k) {
+        int n= nums.size();
+        vector<int>v;
+    deque<int> dq;
+     for (int i = 0; i < k; ++i) {
 
-        deque<int> maxi(k);
-        vector<int> ans;
+        while (!dq.empty() && nums[i] >= nums[dq.back()])
+            dq.pop_back(); 
+
+
+        dq.push_back(i);
+    }
+
+    for (int i=k; i < n; ++i) {
 
-        for(int i = 0; i < k; i++) {
-
-            while(!maxi.empty() && nums[maxi.back()] <= nums[i]) {
-                maxi.pop_back();
-            }
-            maxi.push_back(i);
-        }
-        ans.push_back(nums[maxi.front()]);
+        // cout << nums[dq.front()] << " ";
+        v.push_back(nums[dq.front()] );
+
 
-        for(int i = k; i < nums.size(); i++) {
-
-            //removal
-            while(!maxi.empty() && i-maxi.front() >= k) {
-                maxi.pop_front();
-            }
-
-            //addition
-            while(!maxi.empty() && nums[maxi.back()] <= nums[i]) {
-                maxi.pop_back();
-            }
-
-            maxi.push_back(i);
-
-            ans.push_back(nums[maxi.front()]);
-        }
-        return ans;
+        while ((!dq.empty()) && dq.front() <= i - k)
+            dq.pop_front();
+
+
+        while ((!dq.empty()) && nums[i] >= nums[dq.back()])
+            dq.pop_back();
+
+
+        dq.push_back(i);
+    }
+//    cout << nums[dq.front()];
+   v.push_back(nums[dq.front()]);
+   return v;
+
     }
 };
+
+//************************* 1. O(NlogK) ********************************
+
+// vector<int> maxSlidingWindow(vector<int>& nums, int k) {
+//     vector<int> result;
+//     if (k == 0) return result;
+//     multiset<int> w;
+//     for (int i = 0, n = (int)nums.size(); i < n; i++) {
+//         if (i >= k)
+//             w.erase(w.find(nums[i-k]));
+//         w.insert(nums[i]);
+//         if (i >= k-1)
+//             result.push_back(*w.rbegin());
+//     }
+//     return result;
+// }
+
+//************************* 2. O(NlogN) ***********************************
+
+// vector<int> maxSlidingWindow(vector<int>& nums, int k) {
+//     vector<int> result;
+//     if (k == 0) return result;
+//     priority_queue<pair<int, int>> w;
+//     for (int i = 0, n = (int)nums.size(); i < n; i++) {
+//         while (!w.empty() && w.top().second <= i-k)
+//             w.pop();
+//         w.push(make_pair(nums[i],i));
+//         if (i >= k-1)
+//             result.push_back(w.top().first);
+//     }
+//     return result;
+// }
+
+//***************************** 3. O(N) ********************************
+
+// vector<int> maxSlidingWindow(vector<int>& nums, int k) {
+//     vector<int> result;
+//     if (k == 0) return result;
+//     deque<int> w;
+//     for (int i = 0, n = (int)nums.size(); i < n; i++) {
+//         while (!w.empty() && w.front() <= i-k)
+//             w.pop_front();
+//         while (!w.empty() && nums[w.back()] <= nums[i])
+//             w.pop_back();
+//         w.push_back(i);
+//         if (i >= k-1)
+//             result.push_back(nums[w.front()]);
+//     }
+//     return result;
+// }