Question

Please write simple python program with explanation

Problem statement:

Stock markets are venues where buyers and sellers of shares meet and decide on a price to trade.Eddard is very interested in trading in stock market and he started gathering information of one stock.He has projected market prices for that share over the next n months.Eddard wants to purchase and resell the share to earn profits.He is much worried about the loss that might occur so he wanted to calculate "Minimum loss" according to following rules :

1.The share cannot be sold at a price greater than or equal to the price it was purchased at(i.e. it must be resold at a loss).

2.The share cannot be resold within the same month it was purchased.

Find and print the minimum amount of money Eddard must lose if he buys the share and resells it within the next n months.

Input Format:

The first line contains an integer n,denoting the number of months of share data.

The second line contains n space separated long integers describing the respective values of p1,p2,...pn.

Constraints:

1<=n<=10^5

1<=pi<=10^16

All the market prices are distinct and valid answer exists.

Output Format:

Print a single integer denoting the minimum amount of money Eddard must lose if he buys the share and resells it within the next n months.

Sample Input1:

3

5 10 3

Sample Output1:

2

Explanation:

Eddard buys the stock in month1 at price p1=5 and sells it in month 3 at p3 for a minimal loss of 5-3 = 2 .

Sample Output2:

5

77 82 76 88 80

Sample Output2:

1

Answer 1

n = int(input())                          #taking input of number of month
stocks= list(map(int, input().split()))   #storing the stock price of each month in list
diff = []                                 #declaring list to store the difference
for i in range(len(stocks)-1):            #Outer for loop for initial stocks
  for j in range(len(stocks)-1,i,-1):     #Inner for loop for later stocks
    if(stocks[i]>stocks[j]):              #Condition for the price of stock of next month to be less than the current month
      diff.append(stocks[i]-stocks[j])    #Calculating the difference between current month's and later month's stock price and appending it to list diff
if(len(diff)==0):                         #Checking for situation in which stock price didn't decrease in the next month
  print("Stock can't be sold as there's no month in which stock's price is decreasing") 
else:
  print(min(diff))                       #Printing the minimum value of the list diff in order to determine the minimum loss

Screen shot of code and output:

Explanation:

1. As mentioned the stock is to be sold with loss only, hence we are required to calculate the minimum loss.
2. Also the stock purchased in a month can be sold in next month only.
3. In order to satisfy the condition mentioned in the above point two for loop are used.
4. The outer for loop iterates through the initial stock's price excluding the stock of the last month as there is no month next to the last month and stocks are not allowed to be sold in the same month.
5. Whereas the inner for loop iterates through stock price of next month excluding the current and the previous month as difference will be calculated only between the current and next stock price as stocks are allowed to be sold only in next month.
6. In order to sell it in loss the price of stock in next month should be less than the current month, this condition is checked in the inner for loop.
7. The difference is calculated and appended to the list diff only if the price of next month is less than the current month.
8. After the for loops, both inner and outer complete their iterations the conditions are checked if there was no decrease in stock price, as the stocks can only be sold in loss and in next month and difference calculated only if the price of the stock of the next month is less than the current month.
9. In case there wasn't any decrease in price, there won't be any element in list diff(len(diff)==0), the print function will print "Stock can't be sold as there's no month in which stock's price is decreasing"
10. Otherwise the minimum difference that is the minimum loss will be printed by finding the minimum element of list diff using function min() and passing the whole thing as a parameter to the function print().