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Given an integer \$ n \ge 1 \$, your task is to output an array \$ a \$ consisting of \$ n^2 + 1 \$ integers, such that all possible pairs of integers \$ (x, y) \$ satisfying \$ 1 \le x, y \le n \$ exist as a contiguous subarray in \$ a \$, exactly once.
For example, if \$ n = 2 \$, a valid outpu...