6. Search Insert Position
Given a sorted array and a target value, return its index or the index where it would be inserted.
範例 1:
輸入： nums = [1,3,5,6], target = 5 輸出： 2
範例 2:
輸入： nums = [1,3,5,6], target = 2 輸出： 1
限制條件：
1 <= nums.length <= 10^4
● 已自動儲存第 1 行，第 1 欄