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I want to check if the two arrays are identical (not content wise, but in exact order).
For example:
array1 = [1,2,3,4,5] array2 = [1,2,3,4,5] array3 = [3,5,1,2,4] Array 1 and 2 are identical but 3 is not.
Is there a good way to do this in JavaScript?
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To check if an array contains duplicates: Use the Array. some() method to iterate over the array. Check if the index of the first occurrence of the current value is NOT equal to the index of its last occurrence. If the condition is met, then the array contains duplicates.
You should leverage a hashmap/hashset for a substantially faster O(n) solution: void findDupes(int[] a, int[] b) { HashSet<Integer> map = new HashSet<Integer>(); for (int i : a) map. add(i); for (int i : b) { if (map. contains(i)) // found duplicate! } }
A simple solution would be to use efficient sorting algorithms like Merge Sort, Quicksort, Heapsort, etc., that can solve this problem in O(n. log(n)) time, but those will not take advantage of the fact that there are many duplicated values in the array. A better approach is to use a counting sort.
So, what's wrong with checking each element iteratively?
function arraysEqual(arr1, arr2) { if(arr1.length !== arr2.length) return false; for(var i = arr1.length; i--;) { if(arr1[i] !== arr2[i]) return false; } return true; } You could compare String representations so:
array1.toString() == array2.toString() array1.toString() !== array3.toString() but that would also make
array4 = ['1',2,3,4,5] equal to array1 if that matters to you
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