Added a very interesting problem which has been asked in Microsoft

Gfg/C++/Maximum_of_minimum_for_every_window_size.cpp

@@ -0,0 +1,97 @@
+// Excelling problem came in Microsoft Interviews.
+
+// Implementation in O(N)
+
+#include<bits/stdc++.h>
+using namespace std;
+
+vector<int> previousSmaller(vector<int> &arr, int n){ // Simple Stack problem (used as a function)
+    vector<int> prev(n);
+    stack<int> s;
+    for (int i = 0; i < n; i++) {
+        while (!s.empty() && arr[s.top()] >= arr[i]) {
+            s.pop();
+        }
+        if (s.empty()) {
+            prev[i] = -1;
+        } 
+        else {
+            prev[i] = s.top();
+        }
+        s.push(i);
+    }
+    return prev;
+}
+
+vector<int> nextSmaller(vector<int> &arr, int n) { // Simple Stack problem (used as a function)
+    stack<int> s;
+    vector<int> next(n);
+    for (int i = n - 1; i >= 0; i--) {
+        while (!s.empty() && arr[s.top()] >= arr[i]) {
+            s.pop();
+        }   
+        if (s.empty()) {
+            next[i] = n;
+        } 
+        else {
+            next[i] = s.top();
+        }
+        s.push(i);
+    }
+    return next;
+}
+
+vector<int> maxMinWindow(vector<int> &arr, int n){ // Main Code Function
+
+    // answer[i] will store the maximum of minimum for every window size 
+    vector<int> answer(n, INT_MIN);
+
+    // next[i] will store the index of next smaller element which lie on the right hand side of it
+    vector<int> next = nextSmaller(arr, n);
+
+   //prev[i] will store the index of previous smaller element which lie on the left hand side of it
+    vector<int> prev = previousSmaller(arr, n);
+
+    for (int i = 0; i < n; i++) {
+
+        // Length of the window in which a[i] is minimum
+        int length = next[i] - prev[i] - 1;
+
+        // Update the answer
+        answer[length - 1] = max(answer[length - 1], arr[i]);
+    }
+
+	// Some places in answer[] may not be filled yet.
+	// so fill them by taking maximum
+
+    for (int i = n - 2; i >= 0; i--){
+        answer[i] = max(answer[i], answer[i + 1]);
+    }
+    return answer;
+}
+
+int main(){
+
+    int n;
+
+    cout<<"Enter size of the array : ";
+    cin >> n;
+
+    vector<int> nums(n);
+
+    for(int i = 0 ; i < n ; ++i){
+        cout<<"Enter element "<<i+1<<" : ";
+        cin >> nums[i];
+    }
+
+    vector<int> ans = maxMinWindow(nums , n);
+
+    cout<<"Answer Array : ";
+
+    for(auto x : ans){
+        cout<<x<<" ";
+    }
+
+
+    return 0;
+}