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g0801_0900.s0825_friends_of_appropriate_ages.readme.md Maven / Gradle / Ivy

825\. Friends Of Appropriate Ages

Medium

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`