how to retrun the number in an array that only appears once in python code example
Example 1: Given an array of integers, every element appears thrice except for one which occurs once.
Example 2: Given an array of integers, every element appears thrice except for one which occurs once.
let contacts = new Map()
contacts.set('Jessie', {phone: "213-555-1234", address: "123 N 1st Ave"})
contacts.has('Jessie')
contacts.get('Hilary')
contacts.set('Hilary', {phone: "617-555-4321", address: "321 S 2nd St"})
contacts.get('Jessie')
contacts.delete('Raymond')
contacts.delete('Jessie')
console.log(contacts.size)