/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    const numsToFind = {};

    for (let i=0; i<nums.length; i++) {
        const numToFind = nums[i];
        if (numsToFind[numToFind] >= 0) {
            return [i, numsToFind[numToFind]];
        }
        numsToFind[target - numToFind] = i;
    }
};