Create Object from Two Arrays

Problem Statement

In the problem, you are given two arrays: keysArr and valuesArr. You need to create and return a new object where each key-value pair is determined by correlating keysArr[i] with valuesArr[i]. The complexity is added by the conditions that:

• If a key already exists in the object (due to a previous occurrence in keysArr), that key-value pair is omitted, ensuring only the first occurrence of a key is used.
• Whenever a key is not traditionally a string type, it must be explicitly converted into a string using the String() method. This processing ensures the flexibility in handling various data types as keys.

Examples

Example 1

Input:

keysArr = ["a", "b", "c"], valuesArr = [1, 2, 3]

Output:

{"a": 1, "b": 2, "c": 3}

Explanation:

The keys "a", "b", and "c" are paired with the values 1, 2, and 3 respectively.

Example 2

Input:

keysArr = ["1", 1, false], valuesArr = [4, 5, 6]

Output:

{"1": 4, "false": 6}

Explanation:

First, all the elements in keysArr are converted into strings. We can see there are two occurrences of "1". The value associated with the first occurrence of "1" is used: 4.

Example 3

Input:

keysArr = [], valuesArr = []

Output:

{}

Explanation:

There are no keys so an empty object is returned.

Constraints

• keysArr and valuesArr are valid JSON arrays
• 2 <= JSON.stringify(keysArr).length, JSON.stringify(valuesArr).length <= 5 * 105
• keysArr.length === valuesArr.length

Approach and Intuition

1. Understanding the Output Relationship

From the provided examples, each key from keysArr maps directly to the value at the same index in valuesArr. The object is formed by associating these pairs, and conditionally converting any key to a string format ensures consistency in the object's structure.

2. Handling Duplicates

To abide by the constraint of ignoring subsequent duplicate keys, we must first check if a key has already been added to the object. If so, skip to the next pair, otherwise add the new unique key.

• Approach:
  1. Initialize an empty object.
  2. Iterate over the length of the keysArr.
  3. Convert each key to string (if not already).
  4. If the key isn't already a property of the object, add it with its corresponding value.
  5. Proceed to the next key-value pairs.

3. Edge Cases

Consider the scenario where keysArr is empty. Ideally, the function should return an empty object {}, indicating that there were no keys to process.

• This clean and systematic handling ensures that regardless of the original data types in keysArr or any duplicative keys, the function creates a well-formed object with the expected mappings and maintains the integrity and uniqueness of keys.

Solutions

/**
 * @param {Array} keyList
 * @param {Array} valueList
 * @return {Object}
 */
var buildMap = function(keyList, valueList) {
    const map = {};
    for (const index in keyList) {
        if (!map.hasOwnProperty(keyList[index])) {
            map[keyList[index]] = valueList[index];
        }
    }
    return map;
};