Find Minimum Trips

Problem Overview

• Compute the minimum number of delivery trips, where each trip can carry either two or three packages of the same weight.
• Input: array packageweight[n]; constraints: 1 ≤ n ≤ 1055, 1 ≤ packageweight[i] ≤ 1e9. Output: minimum trips or -1 if some packages cannot be grouped.
• Real-world context: organizing Amazon Prime Day deliveries from a warehouse efficiently.
• From Amazon interviews; a coding interview problem often asked as an interview question.