Question 4
Medium Given an array of positive integers, concatenate each adjacent pair and return the smallest concatenated number; if the array length is odd, treat the final element alone.
Experience
Example array [15, 24, 34, 10, 12, 21, 45, 67] produces pair values 1524, 3410, 1221, and 4567, so the minimum is 1221. Constraints: 1 <= arr.size() <= 100000 and 1 <= arr[i] <= 10000. No candidate solution or performance was reported.