LeetCode: Single Number Solution

Approach

Use a hash table (Map) to store key-value pairs of number and its occurence

Implementation

1var singleNumber = function (nums) {
2  const numOccMap = nums.reduce(
3    (acc, el) => acc.set(el, (acc.get(el) || 0) + 1),
4    new Map()
5  )
6
7  for (const [num, occ] of numOccMap) {
8    if (occ === 1) {
9      return num
10    }
11  }
12}

References

Original problem

MDN Map()