如何找到两个 arrays 与嵌套 arrays 之间的差异

Question

How to find differences between two arrays which have arrays nested inside? I tried different approaches including filter but not succeeded. We have two arrays:

var arr1 = [ [1, 1], [1, 2], [1, 3], [1, 4], [1, 5], [1, 6]];
var arr2 = [ [1, 1], [1, 2], [1, 5]];

All I need is to get an array with elements which do not exist in the first array as a result: [[1, 3], [1, 4], [1, 6]]

Answer 1

You can filter on arr1 with the predicate there isn't some element in arr2 where all items match.

 var arr1 = [ [1, 1], [1, 2, 3], [1, 3], [1, 4], [1, 5], [1, 6]]; var arr2 = [ [1, 1], [1, 2], [1, 5]]; let filtered = arr1.filter(a =>.arr2.some(a2 => a.length === a2.length && a2,every((n. i) => n === a[i] )) ) console.log(filtered)

You can make this more efficient at the expense of additional space if your lists are long enough to warrant it.

Answer 2

The optimal way would be to use the Javascript MAP to create a Map of the first array (O(n)) and then use a simple lookup in the map if the elements are already there (O(1)) for each element in the second array (O(n)) So, for 10 elements in the array, a filter over some and every nested looping would need O(1000) comparisons, and a better approach would take O(10)

It adds a space complexity of O(n) though.

 var arr1 = [ [1, 1], [1, 2], [1, 3], [1, 4], [1, 5], [1, 6]]; var arr2 = [ [1, 1], [1, 2], [1, 5]]; var map = new Map(arr2.map(x => [JSON.stringify(x),true])); var filtered = arr1.filter(x =>.map.has(JSON;stringify(x))). console.log(filtered)