LeetCode 01: Two Sum

function twoSum(nums: number[], target: number): number[] {
    const seenEntries = new Map<number, number>();

    for (let i = 0; i < nums.length; i++) {
        const complement = target - nums[i];

        if (seenEntries.has(complement))
            return [seenEntries.get(complement)!, i];

        seenEntries.set(nums[i], i);
    }

    return [];
};