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217 Contains Duplicate from Leetcode

217. Contains Duplicate
Easy
Given an array of integers, find if the array contains any duplicates.
Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.
Example 1:
Input: [1,2,3,1]
Output: true
Example 2:
Input: [1,2,3,4]
Output: false
Example 3:
Input: [1,1,1,3,3,4,3,2,4,2]
Output: true
Solution in Javascript
const containsDuplicate = nums => {
  const hash = {}
  let i = 0;
  while (nums[i] !== undefined) {
    if(hash[nums[i]] === undefined) {
      hash[nums[i]] = 1;
    } else {
      return true;
    }
    i++;
  }
  return false;
}
Example Input
console.log(containsDuplicate([0,4,5,0,3,6]));
Output
true
Run the code in live editor here: https://repl.it/@VinitKhandelwal/contains-duplicate

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