How should I practice Friend Requests by Age?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Bloomberg LP phone screen problems in FastPrep.

Is Friend Requests by Age associated with Bloomberg LP?

FastPrep tags this as a Bloomberg LP phone screen coding practice problem when the problem catalog has that company and stage context.

Friend Requests by Age

Bloomberg LP● MediumNEW GRADPHONE SCREEN

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Problem statement

Each value in ages is one person's age. A person of age A sends a directed friend request to a different person of age B exactly when both conditions hold:

B > 0.5 * A + 7.
B <= A.

Return the total number of directed friend requests. People of the same age may request each other, but nobody may request themself.

Function

numFriendRequests(ages: int[]) → int

Examples

Example 1

ages = [16,16]return = 2

Each sixteen-year-old sends one request to the other.

Example 2

ages = [16,17,18]return = 2

The seventeen-year-old may request the sixteen-year-old, and the eighteen-year-old may request the seventeen-year-old.

Example 3

ages = [20,30,100,110,120]return = 3

The valid directed requests are 110 -> 100, 120 -> 110, and 120 -> 100.

Constraints

1 <= ages.length <= 20000.
1 <= ages[i] <= 120.