Minimum Swaps

Problem Overview

• Determine the minimum number of swaps needed to arrange items in strictly decreasing popularity, swapping any two items per move.
• Input: int array popularity[n] with unique ratings; Output: int minimum swap count; Constraints: 1 ≤ n ≤ 2×10^5, 1 ≤ popularity[i] ≤ n.
• Real-world context: a shopkeeper reorders shelf items from most to least popular, left to right.
• From Jpmorgan interviews; a coding interview problem and interview question on array ordering and correctness.