创建一个自定义的数据结构，用于评估 O(1) 中的函数
创建一个自定义的数据结构，使其具有以下功能：-
GetLastElement();
RemoveLastElement();
添加元素（）
获取最小值（）
所有函数都应该是 O(1)
问题来源：亚马逊面试题
方法 ：
1）创建具有两个元素的自定义类型结构堆栈，（元素，min_till_now）
2）在这个自定义数据类型上实现功能
C++
// program to demonstrate customized data structure
// which supports functions in O(1)
#include
#include
using namespace std;
const int MAXX = 1000;
// class stack
class stack {
int minn;
int size;
public:
stack()
{
minn = 99999;
size = -1;
}
vector > 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 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. Python3
# 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 mukesh07C#
// program to demonstrate customized data structure
// which supports functions in O(1)
using System;
using System.Collections.Generic;
class GFG {
static List> stack = new List>();
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 pair = new Tuple(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
输出：
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