Is there a way to get key of dictionary without iterating it over?

Question

I have a code like this. And dictionary like this {0: 2, 1: 7, 2: 11, 3: 15}. I am trying to implement hash table using dictionary for array arr=[2,7,11,15]. 2 is stored at index 0, 7 at index 1 and so on.

arr=[2,7,11,15]
target=9
hashmap = {}
for i in range(len(arr)):
    hashmap[i]=arr[i]
for i in range(len(arr)):
    num=arr[i]
    remaining=target-num
    if(hashmap.get(remaining)):
        index=hashmap.index(remaining)
print(index)

I want index of 7 i.e., '1'. Can I do it Without iterating over dictionary inside the outer loop at line 6?

Answer 1

If it's just about getting them enumerated, you could use enumerate for that task. For example: enumerate([2,7,11,15]) would give you an iterator, that you can loop over:

for i, j in enumerate([2,7,11,15]):
    [Do stuff with i and j]

or if you want it in the form of a dictionary or list you can cast that iterator in that form using dict(enumerate([2,7,11,15])).