You are given an array of positive integers?arr. Perform some operations (possibly none) on?arr?so that it satisfies these conditions:

• The value of the?first?element in?arr?must be?1.

• The absolute difference between any 2 adjacent elements must be?less than or equal to?1. In other words,?abs(arr[i] - arr[i - 1]) <= 1?for each?i?where?1 <= i < arr.length?(0-indexed).?abs(x)?is the absolute value of?x.

There are 2 types of operations that you can perform any number of times:

• Decrease?the value of any element of?arr?to a?smaller positive integer.

• Rearrange?the elements of?arr?to be in any order.

Return?the?maximum?possible value of an element in?arr?after performing the operations to satisfy the conditions.

?

Example 1:

Input: arr = [2,2,1,2,1]

Output: 2

Explanation: We can satisfy the conditions by rearranging arr so it becomes [1,2,2,2,1]. The largest element in arr is 2.

Example 2:

Input: arr = [100,1,1000]

Output: 3

Explanation: One possible way to satisfy the conditions is by doing the following: 1. Rearrange arr so it becomes [1,100,1000]. 2. Decrease the value of the second element to 2. 3. Decrease the value of the third element to 3. Now arr = [1,2,3], which satisfies the conditions. The largest element in arr is 3.

Example 3:

Input: arr = [1,2,3,4,5]

Output: 5

Explanation: The array already satisfies the conditions, and the largest element is 5.

?

Constraints:

• 1 <= arr.length <= 105

• 1 <= arr[i] <= 109

給你一個正整數(shù)數(shù)組 arr 。請你對 arr 執(zhí)行一些操作（也可以不進行任何操作），使得數(shù)組滿足以下條件：

arr 中 第一個 元素必須為 1 。

任意相鄰兩個元素的差的絕對值 小于等于 1 ，也就是說，對于任意的 1 <= i < arr.length （數(shù)組下標從 0 開始），都滿足 abs(arr[i] - arr[i - 1]) <= 1 。abs(x) 為 x 的絕對值。

你可以執(zhí)行以下 2 種操作任意次：

減小 arr 中任意元素的值，使其變?yōu)橐粋€ 更小的正整數(shù) 。

重新排列 arr 中的元素，你可以以任意順序重新排列。

請你返回執(zhí)行以上操作后，在滿足前文所述的條件下，arr 中可能的 最大值 。

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依次判斷遍歷即可，只是沒箱單會是中等題目；

下面是代碼：

Runtime:?5 ms, faster than?96.26%?of?Java?online submissions for?Maximum Element After Decreasing and Rearranging.

Memory Usage:?56.8 MB, less than?27.10%?of?Java?online submissions for?Maximum Element After Decreasing and Rearranging.