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# 0825. Friends Of Appropriate Ages

<https://leetcode.com/problems/friends-of-appropriate-ages>

## Description

There are `n` persons on a social media website. You are given an integer array `ages` where `ages[i]` is the age of the `ith` person.

A Person `x` will not send a friend request to a person `y` (`x != y`) if any of the following conditions is true:

* `age[y] <= 0.5 * age[x] + 7`
* `age[y] > age[x]`
* `age[y] > 100 && age[x] < 100`

Otherwise, `x` will send a friend request to `y`.

Note that if `x` sends a request to `y`, `y` will not necessarily send a request to `x`. Also, a person will not send a friend request to themself.

Return *the total number of friend requests made*.

**Example 1:**

```
**Input:** ages = [16,16]
**Output:** 2
**Explanation:** 2 people friend request each other.
```

**Example 2:**

```
**Input:** ages = [16,17,18]
**Output:** 2
**Explanation:** Friend requests are made 17 -> 16, 18 -> 17.
```

**Example 3:**

```
**Input:** ages = [20,30,100,110,120]
**Output:** 3
**Explanation:** Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.
```

**Constraints:**

* `n == ages.length`
* `1 <= n <= 2 * 104`
* `1 <= ages[i] <= 120`

## ac

```java
```