Leetcode day1-Array

Array: consecutive memory, a set of same data type elements

access: O(1)
search: O(N)
insert: O(N)
delete: O(N)

create: int[] a = {1,2,3};
           int[] b = new int[]{1,2,3};
           int[] c = new int[3];
           ArrayList<Integer> arr = new ArrayList<>();
add:  arr.add(value);
        arr.add(index, value);
update: arr.set(index, newValue);
delete: arr.remove(value);
search: arr.contains(value);
order: Arrays.sort(nums);
         Collections.sort(arr);
reverse order: Arrays.sort(nums, Collections.reverseOrder());
                     Collections.sort(arr, Collections.reverseOrder());

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