Leetcode 825. Friends Of Appropriate Ages

Count the number of ordered pairs (x → y), x ≠ y, such that age[y] > 0.5*age[x] + 7, age[y] ≤ age[x], and not (age[y] > 100 and age[x] < 100). The core challenge is efficiently counting pairs that satisfy these age-based inequalities (ages are bounded 1..120) without checking all O(n^2) pairs.