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# 0561. Array Partition I

<https://leetcode.com/problems/array-partition-i>

## Description

Given an integer array `nums` of `2n` integers, group these integers into `n` pairs `(a1, b1), (a2, b2), ..., (an, bn)` such that the sum of `min(ai, bi)` for all `i` is **maximized**. Return *the maximized sum*.

**Example 1:**

```
**Input:** nums = [1,4,3,2]
**Output:** 4
**Explanation:** All possible pairings (ignoring the ordering of elements) are:
1. (1, 4), (2, 3) -> min(1, 4) + min(2, 3) = 1 + 2 = 3
2. (1, 3), (2, 4) -> min(1, 3) + min(2, 4) = 1 + 2 = 3
3. (1, 2), (3, 4) -> min(1, 2) + min(3, 4) = 1 + 3 = 4
So the maximum possible sum is 4.
```

**Example 2:**

```
**Input:** nums = [6,2,6,5,1,2]
**Output:** 9
**Explanation:** The optimal pairing is (2, 1), (2, 5), (6, 6). min(2, 1) + min(2, 5) + min(6, 6) = 1 + 2 + 6 = 9.
```

**Constraints:**

* `1 <= n <= 104`
* `nums.length == 2 * n`
* `-104 <= nums[i] <= 104`

## ac

```java
```