Merge pull request #1165 from akshaymagar2003/main

Created Stack with max API

Author: akgmage

Stacks/Stack_with_max_API.cpp

@@ -0,0 +1,44 @@
+/*
+Time Complexity of all Operations is O(1)
+Space Complexity is O(n)
+In this implementation, we use two stacks: s is the main stack that holds the elements of the stack, and max_s is a secondary stack that holds the maximum values in s. When a new value is pushed onto the stack, we compare it with the current maximum value in max_s and add it to max_s if it's greater than or equal to the current maximum.
+*/
+#include <stack>
+using namespace std;
+
+class MaxStack {
+private:
+    stack<int> s;       // Main stack that holds the elements of the stack
+    stack<int> max_s;   // Secondary stack that holds the maximum values in s
+
+public:
+    void push(int val) {
+        s.push(val);    // Push the value onto the main stack
+        if (max_s.empty() || val >= max_s.top()) {
+            // If max_s is empty or the new value is greater than or equal to the current maximum,
+            // push the value onto max_s
+            max_s.push(val);
+        }
+    }
+
+    void pop() {
+        if (s.top() == max_s.top()) {
+            // If the top value of s is equal to the top value of max_s, it means that the top value
+            // of s is the current maximum, so we need to pop it from max_s as well
+            max_s.pop();
+        }
+        s.pop();    // Pop the value from the main stack
+    }
+
+    int top() {
+        return s.top(); // Return the top value of the main stack
+    }
+
+    int max() {
+        return max_s.top(); // Return the top value of max_s, which is the maximum value in the stack
+    }
+
+    bool empty() {
+        return s.empty();   // Check if the main stack is empty
+    }
+};