In this LeetCode coding problem, we are given two arrays arr1 and arr2, for which we have to return a new array joinedArray. All the objects in each of the two inputs arrays will contain an id field that has an integer value.
joinedArray is an array formed by merging both the arraysarr1 and arr2 based on their id key. The length of joinedArray should be the length of unique values of id. The returned array should be sorted in ascending order based on the id key
Solution: Using Frequency Counter approach
/**
* @param {Array} arr1
* @param {Array} arr2
* @return {Array}
*/
const join = function(arr1, arr2) {
const ob = {};
for(const i of arr1) {
ob[i.id] = i;
}
for(const i of arr2) {
ob[i.id] = ob[i.id] ? {...ob[i.id], ...i} : i;
}
return Object.values(ob);
};Test Cases:
Example 1: There are no duplicate ids so arr1 is simply concatenated with arr2.
Input:
arr1 = [
{"id": 1, "x": 1},
{"id": 2, "x": 9}
],
arr2 = [{"id": 3, "x": 5}]
Output:
[
{"id": 1, "x": 1},
{"id": 2, "x": 9},
{"id": 3, "x": 5}
]Example 2: The two objects with common id are merged together. The keys from arr2 override the values in arr1. Rest of the array gets concatenated normally.
arr1 = [
{"id": 1, "x": 2, "y": 3}, {"id": 2, "x": 3, "y": 6}
],
arr2 = [
{"id": 2, "x": 10, "y": 20}, {"id": 3, "x": 0, "y": 0}
]
Output:
[
{"id": 1, "x": 2, "y": 3},
{"id": 2, "x": 10, "y": 20},
{"id": 3, "x": 0, "y": 0}
]Example 3:
Input:
arr1 = [{"id": 1, "b": {"b": 94},"v": [4, 3], "y": 48}]
arr2 = [ {"id": 1, "b": {"c": 84}, "v": [1, 3]}]
Output: [
{"id": 1, "b": {"c": 84}, "v": [1, 3], "y": 48}
]Performance:
