Create a customized data structure which evaluates functions in O(1) Last Updated : 05 Jul, 2025 Summarize Suggest changes Share Like Article Like Report Create a customized data structure such that it has functions :- GetLastElement(); RemoveLastElement(); AddElement() GetMin()All the functions should be of O(1)Question Source : amazon interview questionsApproach : create a custom stack of type structure with two elements, (element, min_till_now) implement the functions on this custom data type Implementation: C++ // program to demonstrate customized data structure // which supports functions in O(1) #include <iostream> #include <vector> using namespace std; const int MAXX = 1000; // class stack class stack { int minn; int size; public: stack() { minn = 99999; size = -1; } vector<pair<int, int> > arr; int GetLastElement(); int RemoveLastElement(); int AddElement(int element); int GetMin(); }; // utility function for adding a new element int stack::AddElement(int element) { if (size > MAXX) { cout << "stack overflow, max size reached!\n"; return 0; } if (element < minn) minn = element; arr.push_back(make_pair(element, minn)); size++; return 1; } // utility function for returning last element of stack int stack::GetLastElement() { if (size == -1) { cout << "No elements in stack\n"; return 0; } return arr[size].first; } // utility function for removing last element successfully; int stack::RemoveLastElement() { if (size == -1) { cout << "stack empty!!!\n"; return 0; } // updating minimum element if (size > 0 && arr[size - 1].second > arr[size].second) { minn = arr[size - 1].second; } arr.pop_back(); size -= 1; return 1; } // utility function for returning min element till now; int stack::GetMin() { if (size == -1) { cout << "stack empty!!\n"; return 0; } return arr[size].second; } // Driver code int main() { stack s; int success = s.AddElement(5); if (success == 1) cout << "5 inserted successfully\n"; success = s.AddElement(7); if (success == 1) cout << "7 inserted successfully\n"; success = s.AddElement(3); if (success == 1) cout << "3 inserted successfully\n"; int min1 = s.GetMin(); cout << "min element :: " << min1 << endl; success = s.RemoveLastElement(); if (success == 1) cout << "removed successfully\n"; success = s.AddElement(2); if (success == 1) cout << "2 inserted successfully\n"; success = s.AddElement(9); if (success == 1) cout << "9 inserted successfully\n"; int last = s.GetLastElement(); cout << "Last element :: " << last << endl; success = s.AddElement(0); if (success == 1) cout << "0 inserted successfully\n"; min1 = s.GetMin(); cout << "min element :: " << min1 << endl; success = s.RemoveLastElement(); if (success == 1) cout << "removed successfully\n"; success = s.AddElement(11); if (success == 1) cout << "11 inserted successfully\n"; min1 = s.GetMin(); cout << "min element :: " << min1 << endl; return 0; } Java // program to demonstrate customized data structure // which supports functions in O(1) import java.util.ArrayList; public class Gfg { // class Pair static class Pair{ int element; int minElement; public Pair(int element, int minElement) { this.element = element; this.minElement = minElement; } } int min; ArrayList<Pair> stack = new ArrayList<>(); public Gfg() { this.min = Integer.MAX_VALUE; } // utility function for adding a new element void addElement(int x) { if(stack.size() == 0 || x < min) { min=x; } Pair pair = new Pair(x,min); stack.add(pair); System.out.println(x + " inserted successfully"); } // utility function for returning last element of stack int getLastElement() { if (stack.size() == 0) { System.out.println("UnderFlow Error"); return -1; } else { return stack.get(stack.size() - 1).element; } } // utility function for removing last element successfully; void removeLastElement() { if (stack.size() == 0) { System.out.println("UnderFlow Error"); } else if (stack.size() > 1) { min=stack.get(stack.size() - 2).minElement; } else { min=Integer.MAX_VALUE; } stack.remove(stack.size() - 1); System.out.println("removed successfully"); } // utility function for returning min element till now; int getMin() { if (stack.size() == 0) { System.out.println("UnderFlow Error"); return -1; } return stack.get(stack.size() - 1).minElement; } // Driver Code public static void main(String[] args) { Gfg newStack = new Gfg(); newStack.addElement(5); newStack.addElement(7); newStack.addElement(3); System.out.println("min element :: "+newStack.getMin()); newStack.removeLastElement(); newStack.addElement(2); newStack.addElement(9); System.out.println("last element :: "+newStack.getLastElement()); newStack.addElement(0); System.out.println("min element :: "+newStack.getMin()); newStack.removeLastElement(); newStack.addElement(11); System.out.println("min element :: "+newStack.getMin()); } } // This code is contributed by AkashYadav4. Python # Program to demonstrate customized data structure # which supports functions in O(1) import sys stack = [] Min = sys.maxsize # Utility function for adding a new element def addElement(x): global Min, stack if (len(stack) == 0 or x < Min): Min = x pair = [x, Min] stack.append(pair) print(x, "inserted successfully") # Utility function for returning last # element of stack def getLastElement(): global Min, stack if (len(stack) == 0): print("UnderFlow Error") return -1 else: return stack[-1][0] # Utility function for removing last # element successfully; def removeLastElement(): global Min, stack if (len(stack) == 0): print("UnderFlow Error") elif (len(stack) > 1): Min = stack[-2][1] else: Min = sys.maxsize stack.pop() print("removed successfully") # Utility function for returning min # element till now; def getMin(): global Min, stack if (len(stack) == 0): print("UnderFlow Error") return -1 return stack[-1][1] # Driver code addElement(5) addElement(7) addElement(3) print("min element ::", getMin()) removeLastElement() addElement(2) addElement(9) print("Last element ::", getLastElement()) addElement(0) print("min element ::", getMin()) removeLastElement() addElement(11) print("min element ::", getMin()) # This code is contributed by mukesh07 C# // program to demonstrate customized data structure // which supports functions in O(1) using System; using System.Collections.Generic; class GFG { static List<Tuple<int,int>> stack = new List<Tuple<int,int>>(); static int min = Int32.MaxValue; // utility function for adding a new element static void addElement(int x) { if(stack.Count == 0 || x < min) { min=x; } Tuple<int,int> pair = new Tuple<int,int>(x,min); stack.Add(pair); Console.WriteLine(x + " inserted successfully"); } // utility function for returning last element of stack static int getLastElement() { if (stack.Count == 0) { Console.WriteLine("UnderFlow Error"); return -1; } else { return stack[stack.Count - 1].Item1; } } // utility function for removing last element successfully; static void removeLastElement() { if (stack.Count == 0) { Console.WriteLine("UnderFlow Error"); } else if (stack.Count > 1) { min=stack[stack.Count - 2].Item2; } else { min=Int32.MaxValue; } stack.RemoveAt(stack.Count - 1); Console.WriteLine("removed successfully"); } // utility function for returning min element till now; static int getMin() { if (stack.Count == 0) { Console.WriteLine("UnderFlow Error"); return -1; } return stack[stack.Count - 1].Item2; } static void Main() { addElement(5); addElement(7); addElement(3); Console.WriteLine("min element :: "+getMin()); removeLastElement(); addElement(2); addElement(9); Console.WriteLine("Last element :: "+getLastElement()); addElement(0); Console.WriteLine("min element :: "+getMin()); removeLastElement(); addElement(11); Console.WriteLine("min element :: "+getMin()); } } // This code is contributed by divyeshrabadiya07. JavaScript <script> // program to demonstrate customized data structure // which supports functions in O(1) let min; let stack = []; min = Number.MAX_VALUE // utility function for adding a new element function addElement(x) { if(stack.length == 0 || x < min) { min=x; } let pair = [x,min]; stack.push(pair); document.write(x + " inserted successfully" + "</br>"); } // utility function for returning last element of stack function getLastElement() { if (stack.length == 0) { document.write("UnderFlow Error" + "</br>"); return -1; } else { return stack[stack.length - 1][0]; } } // utility function for removing last element successfully; function removeLastElement() { if (stack.length == 0) { document.write("UnderFlow Error" + "</br>"); } else if (stack.length > 1) { min=stack[stack.length - 2][1]; } else { min=Number.MAX_VALUE; } stack.pop(); document.write("removed successfully" + "</br>"); } // utility function for returning min element till now; function getMin() { if (stack.length == 0) { document.write("UnderFlow Error" + "</br>"); return -1; } return stack[stack.length - 1][1]; } addElement(5); addElement(7); addElement(3); document.write("min element :: "+getMin() + "</br>"); removeLastElement(); addElement(2); addElement(9); document.write("Last element :: "+getLastElement() + "</br>"); addElement(0); document.write("min element :: "+getMin() + "</br>"); removeLastElement(); addElement(11); document.write("min element :: "+getMin() + "</br>"); // This code is contributed by rameshtravel07. </script> Output5 inserted successfully 7 inserted successfully 3 inserted successfully min element :: 3 removed successfully 2 inserted successfully 9 inserted successfully Last element :: 9 0 inserted successfully min element :: 0 removed successfully 11 inserted successfully min element :: 2Time complexity: Each function runs in O(1)Auxiliary space: O(n) for stack Advertise with us Next Article Implement Stack and Queue using Deque M msdeep14 Similar Reads Stack Data Structure A Stack is a linear data structure that follows a particular order in which the operations are performed. 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