Leetcode #1 - Two Sum


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Question & Examples

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order.

Example 1

  • Input: nums = [2,7,11,15], target = 9
  • Output: [0,1]
  • Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2

  • Input: nums = [3,2,4], target = 6
  • Output: [1,2]

Example 3

  • Input: nums = [3,3], target = 6
  • Output: [0,1]

My Solution

// a function which accpets an array and a target
function twoSum(nums, target) {
    // loop over the first array
    for (let i = 0; i < nums.length; i++) {
        // extract the value using the index and assign to variable
        const firstNum = nums[i]
        // loop over the said array again instead starting from a +1 index
        for (let y = i + 1; y < nums.length; y++) {
            // extract the value using the index and assign to variable
            const secondNum = nums[y]
            const addedNum = firstNum + secondNum
            // try the addition to see if two numbers add up to target
            if (addedNum === target) {
                return [i, y]
            }
        }
    }
}

Time Complexity: O(n^2)


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