Last Stone Weight

Problem Overview

• Given stone weights, repeatedly smash the two largest; equal weights vanish, otherwise replace with their difference; return the last stone’s weight or 0.
• Input: int weights[n]; Output: integer; Constraints: 1 ≤ n ≤ 1e5, 1 ≤ weights[i] ≤ 10^9.
• Real-world context: a quarry-worker reducing stones by smashing.
• From Factset interviews; a classic coding interview problem and interview question.