Coding challenge

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.

examples:

Input: [1,2,3,1]
Output: true

Input: [1,2,3,4]
Output: false

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

Breakdown and Discussion of challenge

The challenge is asking for the function to be able to find ANY duplicate values. Whenever the input is an array and it requires to find matching values my immediate thought to help me find a solution is to use an object. The object can be use to map out all the given inputs from the array to the object and check against the given array's values to see if the values have been assigned already and there is a match.

Approach

Create an empty object and a for loop. Inside the for loop set an if statement where we ask: is the value in the array inside the object? if so return true . Followed by taking each of the values from the array and mapping them to the object's keys, setting each of the object's values to true. Lastly the function return false if no match is found.

time complexity

Mapping out array values to the object will take the same amount of operations as the number of input increases making this O(n).

space complexity

There is use of only one object match to store the key/value pairs from the given array nums .
Key maps to each array value and each of the key's value is set to true, giving it a space complexity of O(n).

Code

function containsDuplicate(nums) {
    const match = {};
    for (let i = 0; i < nums.length; i++) {
        if (nums[i] in match) return true;
        
        match[nums[i]] = true;
    }
    return false;
};

Road to 170

LC: 1

This is the first Leetcode challenge of the 170 challenges from the LeetCode Patterns by Sean Prashad