Evaluate all possible combinations of values in a set against a specified value-CodePudding

I have a homework problem that requires me to write a function that given an integer k and a list of n unordered integers A, determines if there is a distinct pair of integers in A that sum to k.

I'm struggling to get the function to evaluate all possible combinations of the values in the list. As soon as it gets a pair that does not sum to k it stops. If anyone has any suggestions / tips, I'd greatly appreciate it. I'm not looking for the outright answer, just a nudge in the right direction.

Here is what I have so far:

def sumsToK(k, list1):
    newSet = set(list1) #creates set based on list1 to remove any duplicate values
    print (newSet)
    newSet = list(newSet) #convert back to list so I can iterate through values
    for i in range(len(newSet)):
        for j in range(i 1, len(newSet)):
            print(newSet[i],newSet[j])
            if (newSet[i])   (newSet[j]) == k:
                return (print('There is at least one pair if integers that adds up to k'))
            else:
                return(print('There are is no pair of distinct integers that adds up to k'))

k = 9
list1 = [1, 2, 3, 4, 5, 5, 5, 6, 7, 8, 9, 10] #Multiple distinct pairs will sum to 9

print ((sumsToK(k, list1)))

CodePudding user response：

As soon as it gets a pair that does not sum to k it stops

That's normal given your code: you return immediately at the first iteration, whether you did find a pair or did not find a pair.

Remove the second return and you are all set:

def sumsToK(k, list1):
    newSet = set(list1) #creates set based on list1 to remove any duplicate values
    print (newSet)
    newSet = list(newSet) #convert back to list so I can iterate through values
    for i in range(len(newSet)):
        for j in range(i 1, len(newSet)):
            print(newSet[i],newSet[j])
            if (newSet[i])   (newSet[j]) == k:
                return('There is at least one pair if integers that adds up to k')
            else:
                # it's important not to return anything here otherwise you
                # exit the loop :)
                print('This is not a pair of distinct integers that adds up to k')

k = 9
list1 = [1, 2, 3, 4, 5, 5, 5, 6, 7, 8, 9, 10] #Multiple distinct pairs will sum to 9

print ((sumsToK(k, list1)))

It gives me:

set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
(1, 2)
(1, 3)
(1, 4)
(1, 5)
(1, 6)
(1, 7)
(1, 8)
There is at least one pair if integers that adds up to k

By the way, do not return print statements, just return the string, or print it (not both!).