Stock Span Problem

"The Stock Span Problem" comes under the financial aspect. The stock span for each day's stock price is determined in this problem. Its span is the greatest number of consecutive days shortly before any given day when the stock price is less than or equal to the stock price on those days.

The greatest number of consecutive days just before the given day for which the stock's price on the present day is less than or equal to its price on the given day is described as the span Si of the stock's price on that day.

For example, if an array of seven-day prices is supplied as 100, 80, 60, 70, 60, 75, 85, the span values for the seven days are 1, 1, 1, 2, 1, 4, 6.

There are two methods to find the solution to this Stock Span problem. These two methods are:

Inefficient method
Efficient method

In this stock span problem, traverse the price array in the input. While items on the left side are smaller, traverse elements on the left side and increase the span value of each visited element.

Now let's understand the Stock span problem with the help of codes written in three different programming languages C++, Java, and Python.

C++ Code

Let's understand this problem with the help of the following C++ code.

// A sample C++ program to calculate stock span values  
#include <bits/stdc++.h> 
using namespace std;   
// Fills array S[] with span values  
void calculateSpan(int price[], int n, int S[])  
{  
    // Span value of first day is always 1  
    S[0] = 1;   
    // Calculate span value of remaining days   
    // by linearly checking previous days  
    for (int i = 1; i < n; i++)  
    {  
        S[i] = 1; // Initialize span value   
        // Traverse left while the next element   
        // on left is smaller than price[i]  
        for (int j = i - 1; (j >= 0) &&  
                (price[i] >= price[j]); j--)  
            S[i]++;  
    }  
}   
// A utility function to print elements of array  
void printArray(int arr[], int n)  
{  
    for (int i = 0; i < n; i++)  
        cout << arr[i] << " ";  
}    
// Driver code  
int main()  
{  
    int size_arr = 0;
    cout<<"Enter the size of the span array::\n";
    cin>>size_arr;
    int price[size_arr]; //= new int[size_arr];//{ 10, 4, 5, 90, 120, 80 };  
    int n = size_arr;//sizeof(price) / sizeof(price[0]);  
    int S[n];  
    int data;
    int count = 0;
      char ch;
            // Do-while loop
            // Do part for performing actions
            do
            // Menu is displayed
            // Users enter 'y' to continue 'n' if
            // entered by user , the program terminates
            {
                  // Menu
                  // Display messages
                  cout<<"Please Choose one of the Operations listed below::\n";
                  cout<<"1. To Insert a new span value to the array.\n";
                  cout<<"2. To Calculate span value entered in array.\n";
                  cout<<"3. To Display the Calculated span values.\n";
                  cout<<"\n";               
                  int choice;
                  scanf("%d",&choice);
                  // Switch case
                  switch (choice) {
                  // Case 1
                  case 1:
                        cout<<"Enter the span value that you want to add to array :\n";
                        cin>>data;                        
                        price[count++] = data;
                        // Display message
                        cout<<"Data Added Successfully.\n";
                        // Break statement to terminate a case
                        break;
                  // Case 2
                  case 2:
                        // Display message
                        calculateSpan(price, n, S);
                        cout<<"Span Values Calculated Successfully.";
                        // Break statement to terminate a case
                        break;
                  // Case 3
                  case 3:
                        // Display message
                        cout<<"New calculated Span values:\n";
                        printArray(S,n);
                        // Break statement to terminate a case
                        break;
                  default:
                        // Print statement
                        cout<<"Please enter a valid option from the menu to proceed further.\n \n";
                        // Break statement
                        break;
                  }
                  cout<<"\nType [N or n] to terminate the program.\nType [Y or y] to continue the program.\n";
                  cin>>ch;                 
            } while (!(ch == 'N' || ch == 'n'));
    return 0;  
}

Output

The above code gives the following output.

Enter the size of the span array::
7
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
16
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
67
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
44
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
93 
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
33
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
2
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
86
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
2
Span Values Calculated Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
3
New calculated Span values:
1 2 1 4 1 1 3 
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
n

In the above c++ code, we have created a class that has the functions to find the span values for the inserted prices of the stocks. The flow of the code is like this: the user is given three choices: add the prices of the stocks to calculate the span value for those inserted stock prices, and then print the calculated span values of the stock prices. The user enters the prices of the stocks; once the prices are added successfully, the calculateSpan() function is called, which calculates the span values for those inserted price values. Finally, with the help of the last option, those span values are printed.

Java Code

Let's understand this problem also with the help of the Java code.

// A sample Java program to calculate stock span values  
import java.util.Arrays; 
import java.util.Stack;
import java.util.Scanner; 
class spanStock{ 
    // A function named calSpan() is written that will be used to calculate the span of the prices of the stocks that are stored in the price array, and those calculated spans corresponding to each price is stored in the integer array S
    static void calSpan(int price[], int n, int S[]){    
        Stack<Integer> st = new Stack<>(); 
        st.push(0);  
        S[0] = 1;   
        for(int i = 1; i < n; i++){   
            while((!st.empty()) && (price[st.peek()] <= price[i])){ 
                st.pop(); 
            } 
            S[i] = (st.empty()) ? (i + 1) : (i - st.peek());   
            st.push(i); 
        }  
    } 
    // A function named display() is written that will be used to print the spans of the prices that are calculated by the calSpan() function
    static void display(int arr[]){ 
        System.out.print("Span of "+arr.length+" days : "); 
        for (int i = 0; i < arr.length; i++)  
            System.out.print(arr[i]+" ");  
    } 
// Main function is written to call the calSpan() function that will be used to calculate the span of the prices of the stocks that are stored in the price array, and those calculated spans corresponding to each price is stored in the integer array S
    public static void main(String[] args){        
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter the size of the span array:: \n");
        int size_arr = scan.nextInt();
        int price[] = new int[size_arr]; 
	int price[] = new int[size_arr]; 
        int n = price.length; 
        int S[] = new int[n];         
        char ch;
        int data;
        int count = 0;
       /*  Perform list operations  */
        do
            {
                System.out.println("Please Choose one of the Operations listed below::");
                System.out.println("1. To Insert a new price value into the array.");
                System.out.println("2. To Calculate span value entered in array.");
                System.out.println("3. To Display the Calculated span values.");
                int choice = scan.nextInt();
                switch (choice)
                    {
                    case 1 :                       
                        System.out.println("Enter the price value that you want to add to the array :\n");
                        data = scan.nextInt();
                        price[count++] = data;
                        // Display message
                        System.out.println("Data Added Successfully.\n");
                        // Break statement to terminate a case
                        break;
                    case 2 :
                        System.out.println("Span Values Calculated Successfully.");
                        calSpan(price,n,S);                
                        break;
                    case 3:
                        System.out.println("New calculated Span values");
                        display(S);
                        break;
                    default :
                        System.out.println("Wrong Entry\n ");
                        break;
                    }
                System.out.println("\nDo you want to continue (Type y or n)\n");
                ch = scan.next().charAt(0);
            }
        while (ch == 'Y'|| ch == 'y');
    } 
}

Output

The above Java code gives the following output.

Enter the size of the span array:: 
9
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
14
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
287
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1 
Enter the price value that you want to add to the array :
32
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
40
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
533
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
6
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
700
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
855
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the price value that you want to add to the array :
9002
Data Added Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
2
Span Values Calculated Successfully.
Do you want to continue (Type y or n)
y
Please Choose one of the Operations listed below::
1. To Insert a new price value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
3
New calculated Span values.
Span of 9 days : 1 2 1 2 5 1 7 8 9 
Do you want to continue (Type y or n)
n

In the above java code, we have created a class that has the functions to find the span values for the inserted prices of the stocks. The flow of the code is like this; the user is given three choices: add the prices of the stocks, calculate the span value for those inserted stock prices, and then print the calculated span values of the stock prices. Now, the user enters the prices of the stocks. Once the prices are added successfully, the calculateSpan() function is called, which calculates the span values for those inserted price values. Finally, with the help of the last option, those span values are printed.

Python

Now we find the solution to this problem through this Python code.

# A sample Python program to calculate stock span values  
class StackSpanProblem:
	# A function named calculateSpan() will be used to calculate the span of the prices of the stocks that are stored in the price array, and those calculated spans corresponding to each price is stored in the integer array S
	def calculateSpan(self,price, n, S):		
		# Span value of first day is always 1
		S[0] = 1
		# Calculate span value of remaining days by linearly
		# checking previous days
		for i in range(1, n, 1):
			S[i] = 1 # Initialize span value	 
			# Traverse left while the next element on left is
			# smaller than price[i]
			j = i - 1
			while (j>= 0) and (price[i] >= price[j]) :
						S[i] += 1
						j -= 1							
	# A utility function to print elements of array
	def printArray(self,arr, n):
		for i in range(n):
			print(arr[i], end = " ")
# Driver program to test above function
price = list()
while True:
	print("Please Choose one of the Operations listed below::")
	print("1. To Insert a new price value into the array.")
	print("2. To Calculate span value entered in array.")
	print("3. To Display the Calculated span values.")
	choice = input()
	if choice==1:
		print("Enter the price value that you want to add to the array :")
		price.append(input())
	elif choice==2:
		calculateSpan(price,len(price),S)
	elif choice==3:
		printArray(S,len(price))
	else:
		print("Inavlid Entry")
	print("Do you want to continue (Type y or n)")
	choice_cont = input()
	if choice_cont=='n':
		break

Output

The above python code produces the following output.

Enter the size of the span array::
7
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
16
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
67
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
44
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
93 
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
33
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
2
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
1
Enter the span value that you want to add to the array :
86
Data Added Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
2
Span Values Calculated Successfully.
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
y
Please Choose one of the Operations listed below::
1. To Insert a new span value into the array.
2. To Calculate span value entered in array.
3. To Display the Calculated span values.
3
New calculated Span values:
1 2 1 4 1 1 3 
Type [N or n] to terminate the program.
Type [Y or y] to continue the program.
n

In the above python code, we have created a class that has the functions to find the span values for the inserted prices of the stocks. The flow of the code is like this; the user is given three choices: add the prices of the stocks, calculate the span value for those inserted stock prices, and then print the calculated span values of the stock prices. Now, the user enters the prices of the stocks. Once the prices are added successfully, the calculateSpan() function is called, which calculates the span values for those inserted price values. Finally, with the help of the last option, those span values are printed.

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