Question

Implement these in Python 3 preferably.

Task: Implement the following algorithms to solve the Stock Span Problem using the ADT for a Stack in ython. The implementation of the ADT of a Stack (10 points) Implementation of computeSpans1 (20 points) Implementation of computeSpan2 (30 points) Provide the derived computational complexity of both computeSpans1 and computeSpans2 (40 points) Algorithm computeSpans1 (P) Input: an n-element list P of numbers such that P[i] is the prices of the stock on day I Output: an n-element list s of numbers such that S[i] is the span of the stock on day I for i ← 0 to n-1 do k←0; done ← false while (k<=1) or not done if P[1-k] P[i] k← then true <= k+1 else done return S Algorithm computeSpans2 (P) Input: an n-element list P of numbers such that P[i] is the prices of the stock on day I Output: an n-element list s of numbers such that S[i] is the span of the stock on day I Let D be an empty stack for i ← 0 to n-1 do h←0; done ← false while not (D.isEmpty ) or done) do if P[ǐ] then >= P[D.top ( )] else done ← true D.pop ( ) if D.isEmpty() then h←-1 else h< D . top ( ) D.push (i) return S

Answer 1

computeSpans1.py
-------------------------------------------------------------
import time
def computeSpans1(P):
    S = []
    start = time.time()
    for i in range(len(P)):
        k = 0
        done = False
        while (k<=i) and not done:
                if (P[i-k] <= P[i]):
                    k = k+1
                else:
                    done = True
        S.append(k)
    end = time.time()
    return S, end
P=[4,3,1,2,1,3,7]
S=computeSpans1(P)
print(S)
----------------------------------------------------------
computeSpans2.py
-----------------------------------
from Stack2 import *
import time
def computeSpans2(P):
    S = []
    D = Stack()

    start = time.time()
    for i in range(len(P)):
        h = 0
        done = False
        while not (D.is_empty() or done):
            if P[i] >= P[D.peek()]:
                D.pop()
            else:
                done = True
        if D.is_empty():
            h = -1
        else:
            h = D.peek()

        S.append(i - h)
        D.push(i)
    end = time.time()
    return S, end
prices = [4, 3, 1, 2, 1, 3, 7]
print(computeSpans2(prices))
-----------------------------------------------------------
Stack.py
----------------------------------
class Stack:
    def __init__(self):
        self.items = []

    def is_empty(self):
        if not self.items:
            return True
        else:
            return False

    def push(self, items):
        self.items.append(items)

    def pop(self):
        return self.items.pop()

    def peek(self):
        return self.items[len(self.items) - 1]

    def size(self):
        return len(self.items)