Two Sums

twoSum.js

// https://leetcode.com/problems/two-sum/

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {    
    /* First Solution (Brute Force)
    let indexes = [];
    for(let i=0; i<nums.length; i++){
        for(let j= i + 1; j<nums.length; j++){
            if((nums[i] + nums[j]) == target){
                indexes = [i, j];
                return indexes;
            }
        }
    }
    */
    
    // num > 0 ? num : num * -1
    // if (num > 0 ) {return num; } else {return (num * -1); }  
    // Math.abs(n) == (n > 0 ? n : n * -1)
    
    // nums = [2, 7, 11, 15]
    // subs = [7, 2, 2, 6]
    
    
    /* This is a trap!!!
    let subtracts = nums.map( num => Math.abs(num - target));

    for (let i = 0; i< nums.length; i++){
        let j = subtracts.indexOf(nums[i]);
        if(j !== -1){
            return [i,j];
        }
    }
    */
    
    /*
    let dictionary = {
        pen: 'boli', 
        paper : 'papel', 
        notebook: 'libreta', 
        eraser: 'goma'
    };
    
    console.log(dictionary['tomato'])
    */
    
    let substDict = {}
    let solutions = [];
    
    for(let i=0; i < nums.length; i++){
        let subst = target - nums[i];
        substDict[subst] = i;
    }
        
    for(let j = 0; j < nums.length; j++){
        if(substDict[nums[j]] !== undefined){
            let secondIndex = substDict[nums[j]];
            return [j, secondIndex ];
        }
    }
    
    return solutions;
    
    // 1. if there is more solutions, add that to solutions array nums = [2,7,4,5] target = 9
    // 2. remove duplicates [[0,1], [1,0]]
    // 3. Why this is not working? nums = [3,2,4] target = 6
};