Create a customized data structure which evaluates functions in O(1)
Last Updated :
08 Sep, 2022
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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 questions
Approach :
- create a custom stack of type structure with two elements, (element, min_till_now)
- implement the functions on this custom data type
Implementation:
// 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;
}
// 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.
# 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
// 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.
<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>
Output
5 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 :: 2
Time complexity: Each function runs in O(1)
Auxiliary space: O(n) for stack
