Solution: First Non-Repeating Integer in an Array—Hashing
Let’s solve the First Non-Repeating Integer in an Array—Hashing problem.
We'll cover the following
Statement
Given an array of integers, nums
, find the first non-repeating integer in the array.
Constraints:
nums.length
nums[i]
Solution
We track the frequency of each element in the array using an unordered map, which stores key-value pairs. The keys represent the elements of the array, and the values indicate how many times each element occurs.
Initialize an empty unordered map,
counts
, to store the counts of each element.Iterate through the array of elements.
If the element is already a key in
counts
, increment its value byto represent its count. If the element is not in
counts
, add it to the unordered map with a count of.
Iterate through the array again.
Check the count of each element in
counts
.Return the first element with a count of
.
Let’s look at the illustration below to better understand the solution:
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