Minimum Track Sensor Swaps
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Medium
Minimum Track Sensor Swaps
Two sensor tracks record one reading at each timestamp. At any timestamp, you may swap the two readings at that same index. Find the minimum number of swaps needed so both tracks become strictly increasing from left to right. The input is guaranteed to have at least one valid answer.
Examples
Example 1
Input:
upper = [1,3,5,4], lower = [1,2,3,7]
Output:
1
Explanation: Swap the readings at the last timestamp.
Approach hint
At each index, only two states matter: swapped or not swapped.
Common mistake
Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.
solution.cpp