First repeated ID

Write code · Basic · §4.1 Remembering what you have seen

ids holds IDs in the order the sign-up requests came in. Complete the function solution, which goes through ids in order and returns the first ID that has already appeared earlier in the list.

If no ID is repeated, return an empty string "".

Function

solution(ids)

Constraints

The length of ids is from 1 to 100,000.
Each ID is a string of lowercase English letters and digits, with a length from 1 to 20.

Examples

ids	result
`['kim', 'lee', 'park', 'lee', 'kim']`	`'lee'`
`['a', 'b']`	`''`

Starter code

def solution(ids):
    answer = ""
    return answer

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