Saturday, September 30, 2023
HomeSoftware EngineeringCalculate the Sum of Pairs in Python

# Calculate the Sum of Pairs in Python

## The problem#

Given a listing of integers and a single sum worth, return the primary two values (parse from the left please) so as of look that add as much as kind the sum.

``````sum_pairs([11, 3, 7, 5],         10)
#              ^--^      3 + 7 = 10
== [3, 7]

sum_pairs([4, 3, 2, 3, 4],         6)
#          ^-----^         4 + 2 = 6, indices: 0, 2 *
#             ^-----^      3 + 3 = 6, indices: 1, 3
#                ^-----^   2 + 4 = 6, indices: 2, 4
#  * whole pair is earlier, and subsequently is the right reply
== [4, 2]

sum_pairs([0, 0, -2, 3], 2)
#  there are not any pairs of values that may be added to supply 2.
== None/nil/undefined (Based mostly on the language)

sum_pairs([10, 5, 2, 3, 7, 5],         10)
#              ^-----------^   5 + 5 = 10, indices: 1, 5
#                    ^--^      3 + 7 = 10, indices: 3, 4 *
#  * whole pair is earlier, and subsequently is the right reply
== [3, 7]
``````

Adverse numbers and duplicate numbers can and can seem.

NOTE: There can even be lists examined of lengths upwards of 10,000,000 parts. Make sure your code doesn’t trip.

## The answer in Python code#

Choice 1:

``````def sum_pairs(lst, s):
cache = set()
for i in lst:
if s - i in cache:
return [s - i, i]
``````

Choice 2:

``````def sum_pairs(ints, s):
num_dic = {}
for num in ints:
if num in num_dic:
return [num_dic[num], num]
else:
num_dic[s - num] = num
``````

Choice 3:

``````def sum_pairs(ints, s):
seen=[]
for merchandise in ints:
if s-item in seen: return [s-item, item]
if merchandise not in seen: seen+=[item]
return None
``````

## Take a look at circumstances to validate our resolution#

``````l1= [1, 4, 8, 7, 3, 15]
l2= [1, -2, 3, 0, -6, 1]
l3= [20, -13, 40]
l4= [1, 2, 3, 4, 1, 0]
l5= [10, 5, 2, 3, 7, 5]
l6= [4, -2, 3, 3, 4]
l7= [0, 2, 0]
l8= [5, 9, 13, -3]

check.describe("Testing For Sum of Pairs")
check.anticipate(sum_pairs(l1, 8) == [1, 7], "Fundamental: %s ought to return [1, 7] for sum = 8" % l1)
check.anticipate(sum_pairs(l2, -6) == [0, -6], "Negatives: %s ought to return [0, -6] for sum = -6" % l2)
check.anticipate(sum_pairs(l3, -7) == None, "No Match: %s ought to return None for sum = -7" % l3)
check.anticipate(sum_pairs(l4, 2) == [1, 1], "First Match From Left: %s ought to return [1, 1] for sum = 2 " % l4)
check.anticipate(sum_pairs(l5, 10) == [3, 7], "First Match From Left REDUX!: %s ought to return [3, 7] for sum = 10 " % l5)
check.anticipate(sum_pairs(l6, 8) == [4, 4], "Duplicates: %s ought to return [4, 4] for sum = 8" % l6)
check.anticipate(sum_pairs(l7, 0) == [0, 0], "Zeroes: %s ought to return [0, 0] for sum = 0" % l7)
check.anticipate(sum_pairs(l8, 10) == [13, -3], "Subtraction: %s ought to return [13, -3] for sum = 10" % l8)
``````
RELATED ARTICLES