solved on 16/12/23

Author: Priyanshu-Ganatra

CS_38_SumOfMinAndMaxElementsOfWindowOfSizeK.cpp

@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// tc : O(n) sc : O(n)
+long long sumOfMaxAndMin(vector<int> &nums, int n, int k)
+{
+    long long ans = 0;    
+    deque<int> dq1, dq2; // store the index of the maximum and minimum elements in the window  
+    // process first k elements - 1st window
+    for (int i = 0; i < k; i++)
+    {
+        // remove the elements which are smaller than the current element because they can't be the maximum element in the window
+        while (!dq1.empty() && nums[i] >= nums[dq1.back()]) 
+            dq1.pop_back();
+        // remove the elements which are greater than the current element because they can't be the minimum element in the window
+        while (!dq2.empty() && nums[i] <= nums[dq2.back()]) 
+            dq2.pop_back();
+        dq1.push_back(i); // add the current element as it can be the maximum element in the window and the next window
+        dq2.push_back(i); // add the current element as it can be the minimum element in the window and the next window
+    }
+    ans += nums[dq1.front()] + nums[dq2.front()]; // add the maximum and minimum element of the previous window in the answer array
+
+
+    // process remaining windows -> remove the element which is out of the window and add the new the element
+    for (int i = k; i < nums.size(); i++)
+    {
+        // remove the front element if it is out of the window
+        if (i - dq1.front() >= k) // if the maximum element is out of the window
+            dq1.pop_front();
+        if (i - dq2.front() >= k) // if the minimum element is out of the window
+            dq2.pop_front();
+
+        // remove the elements which are smaller than the current element because they can't be the maximum element in the window
+        while (!dq1.empty() && nums[i] >= nums[dq1.back()]) 
+            dq1.pop_back();
+
+        // remove the elements which are greater than the current element because they can't be the minimum element in the window
+        while (!dq2.empty() && nums[i] <= nums[dq2.back()]) 
+            dq2.pop_back();
+        dq1.push_back(i); // add the current element as it can be the maximum element in the window and the next window
+        dq2.push_back(i); // add the current element as it can be the mimimum element in the window and the next window
+
+        ans += nums[dq1.front()] + nums[dq2.front()]; // find the ans for the current window
+    }
+    return ans;
+}
+
+int main()
+{
+    vector<int> nums = {1, 2, 3, 4, 5};
+    int k = 3;
+    int n = nums.size();
+    cout << sumOfMaxAndMin(nums, n, k) << endl;
+    return 0;
+}

LC_105_ImplementQueueUsingStacks.cpp

@@ -0,0 +1,74 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class MyQueue
+{
+public:
+    stack<int> s1, s2;
+    MyQueue()
+    {
+    }
+
+    void push(int x)
+    {
+        s1.push(x);
+    }
+
+    int pop()
+    {
+        int pop = -1;
+        if (!s2.empty())
+        {
+            pop = s2.top();
+        }
+        else
+        {
+            while (!s1.empty())
+            {
+                s2.push(s1.top());
+                s1.pop();
+            }
+            pop = s2.top();
+        }
+        s2.pop();
+        return pop;
+    }
+
+    int peek()
+    {
+        int peek = -1; // front element
+        if (!s2.empty())
+        {
+            peek = s2.top();
+        }
+        else
+        {
+            while (!s1.empty())
+            {
+                s2.push(s1.top());
+                s1.pop();
+            }
+            peek = s2.top();
+        }
+        return peek;
+    }
+
+    bool empty()
+    {
+        return s1.empty() && s2.empty();
+    }
+};
+
+int main()
+{
+    MyQueue *obj = new MyQueue();
+    obj->push(1);
+    obj->push(2);
+    int param_2 = obj->pop();
+    int param_3 = obj->peek();
+    bool param_4 = obj->empty();
+    cout << param_2 << endl;
+    cout << param_3 << endl;
+    cout << param_4 << endl;
+    return 0;
+}

LC_106_ImplementStackUsingQueue.cpp

@@ -0,0 +1,49 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class MyStack
+{
+public:
+    queue<int> q;
+    MyStack()
+    {
+    }
+
+    void push(int x)
+    {
+        q.push(x);
+        for (int i = 0; i < q.size() - 1; i++)
+        {
+            q.push(q.front());
+            q.pop();
+        }
+    }
+
+    int pop()
+    {
+        int pop = q.front();
+        q.pop();
+        return pop;
+    }
+
+    int top()
+    {
+        return q.front();
+    }
+
+    bool empty()
+    {
+        return q.empty();
+    }
+};
+
+int main()
+{
+    MyStack *obj = new MyStack();
+    obj->push(1);
+    obj->push(2);
+    cout << obj->top() << endl;
+    cout << obj->pop() << endl;
+    cout << obj->empty() << endl;
+    return 0;
+}