Some people will make friend requests. The list of their ages is given and
ages[i] is the age of the ith person.
Person A will NOT friend request person B (B != A) if any of the following conditions are true:
age[B] <= 0.5 * age[A] + 7
age[B] > age[A]
age[B] > 100 && age[A] < 100
Otherwise, A will friend request B.
Note that if A requests B, B does not necessarily request A. Also, people will not friend request themselves.
How many total friend requests are made?
Input: [16,16] Output: 2 Explanation: 2 people friend request each other.
Input: [16,17,18] Output: 2 Explanation: Friend requests are made 17 -> 16, 18 -> 17.
Input: [20,30,100,110,120] Output: 3 Explanation: Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.
1 <= ages.length <= 20000.
1 <= ages[i] <= 120.