Solution For Interview Question: First Duplication | Asked By Google
Find First Duplicate is one of a classic interview question that has been asked by google which you can solve in codesignal. But if you are looking for a different solution than yours, here's how I solved it.
Given an array
a that contains only numbers in the range from
a.length , find the first duplicate number for which the second occurrence has the minimal index. In other words, if there are more than 1 duplicated numbers, return the number for which the second occurrence has a smaller index than the second occurrence of the other number does. If there are no such elements, return
a = [2, 1, 3, 5, 3, 2], the output should be
firstDuplicate(a) = 3.
- There are
3. The second occurrence of
3has a smaller index than the second occurrence of
2does, so the answer is
a = [2, 2], the output should be
firstDuplicate(a) = 2;
a = [2, 4, 3, 5, 1], the output should be
firstDuplicate(a) = -1.
- Create a hash map to store previously visited numbers
- If the current number already exists on the map then this would the first duplicate number we are looking for