Python Program to find Sum of Negative, Positive Even and Positive Odd numbers in a List

Given a list. The task is to find the sum of Negative, Positive Even, and Positive Odd numbers present in the List.

Examples:

Input: -7 5 60 -34 1 
Output: 
Sum of negative numbers is  -41 
Sum of even positive numbers is  60 
Sum of odd positive numbers is  6

Input: 1 -1 50 -2 0 -3
Output:
Sum of negative numbers is  -6
Sum of even positive numbers is  50
Sum of odd positive numbers is  1

Negative numbers are the numbers less than 0 while positive even numbers are numbers greater than 0 and also divisible by 2. 0 is assumed to be a positive even number, in this case. 

Approach:

• The first approach input a list of numbers from the user.
• Two loops are run, one for the positive numbers and the other for the negative numbers, computing the numbers’ summation.
• If n is the size of the list of numbers,
• it takes O(2n) time complexity, for iterating over the list of numbers twice.

Python3

class Sumofnumbers:

    # find sum of negative numbers
    def negSum(self, list):

        # counter for sum of
        # negative numbers
        neg_sum = 0

        for num in list:

            # converting number
            # to integer explicitly
            num = int(num)

            # if negative number
            if(num < 0):

                # simply add to the
                # negative sum
                neg_sum + = num

        print("Sum of negative numbers is ", neg_sum)

    # find sum of positive numbers
    # according to categories
    def posSum(self, list):

        # counter for sum of
        # positive even numbers
        pos_even_sum = 0

        # counter for sum of
        # positive odd numbers
        pos_odd_sum = 0
        for num in list:

            # converting number
            # to integer explicitly
            num = int(num)

            # if negative number
            if(num >= 0):

                # if even positive
                if(num % 2 == 0):

                    # add to positive
                    # even sum
                    pos_even_sum + = num
                else:

                    # add to positive odd sum
                    pos_odd_sum + = num

        print("Sum of even positive numbers is ",
              pos_even_sum)

        print("Sum of odd positive numbers is ",
              pos_odd_sum)


# input a list of numbers
list_num = [-7, 5, 60, -34, 1]

# creating an object of class
obj = Sumofnumbers()

# calling method for  sum
# of all negative numbers
obj.negSum(list_num)

# calling method for
# sum of all positive numbers
obj.posSum(list_num)

Output:

Sum of negative numbers is  -41
Sum of even positive numbers is  60
Sum of odd positive numbers is  6

The second approach computes the sum of respective numbers in a single loop. It maintains three counters for each of the three conditions, checks the condition and accordingly adds the value of the number in the current sum . If n is the size of the list of numbers, it takes O(n) time complexity, for iterating over the list of numbers once. 

Python3

class Sumofnumbers:
    # find sum of numbers
    # according to categories
    def Sum(self, list):

        # counter for sum
        # of negative numbers
        neg_sum = 0

        # counter for sum of
        # positive even numbers
        pos_even_sum = 0

        # counter for sum of
        # positive odd numbers
        pos_odd_sum = 0

        for num in list:

            # converting number
            # to integer explicitly
            num = int(num)

            # if negative number
            if(num < 0):

                # simply add
                # to the negative sum
                neg_sum += num
            # if positive number
            else:

                # if even positive
                if(num % 2 == 0):

                    # add to positive even sum
                    pos_even_sum + = num
                else:

                    # add to positive odd sum
                    pos_odd_sum + = num
        print("Sum of negative numbers is ",
              neg_sum)
        print("Sum of even positive numbers is ",
              pos_even_sum)
        print("Sum of odd positive numbers is ",
              pos_odd_sum)


# input a list of numbers
list_num = [1, -1, 50, -2, 0, -3]

# creating an object of class
obj = Sumofnumbers()

# calling method for
# largest sum of all numbers
obj.Sum(list_num)

Output: 

Sum of negative numbers is  -6
Sum of even positive numbers is  50
Sum of odd positive numbers is  1