# 1551. Minimum Operations to Make Array Equal

<https://leetcode.com/problems/minimum-operations-to-make-array-equal>

## Description

You have an array `arr` of length `n` where `arr[i] = (2 * i) + 1` for all valid values of `i` (i.e. `0 <= i < n`).

In one operation, you can select two indices `x` and `y` where `0 <= x, y < n` and subtract `1` from `arr[x]` and add `1` to `arr[y]` (i.e. perform `arr[x] -=1`and `arr[y] += 1`). The goal is to make all the elements of the array **equal**. It is **guaranteed** that all the elements of the array can be made equal using some operations.

Given an integer `n`, the length of the array. Return *the minimum number of operations* needed to make all the elements of arr equal.

**Example 1:**

```

**Input:** n = 3
**Output:** 2
**Explanation:** arr = [1, 3, 5]
First operation choose x = 2 and y = 0, this leads arr to be [2, 3, 4]
In the second operation choose x = 2 and y = 0 again, thus arr = [3, 3, 3].
```

**Example 2:**

```

**Input:** n = 6
**Output:** 9
```

**Constraints:**

* `1 <= n <= 10^4`

## ac

```java
```
