You are given a square integer matrix grid of size n x n that is intended to contain every value from $1$ to $n^2$ exactly once. However, one value appears twice in grid, and one value from the range $1$ to $n^2$ does not appear at all.

Return an array of length $2$ where the first element is the repeated value and the second element is the missing value.

Constraints:

• $2 \leq$ n $==$ grid.length $==$ grid[i].length $\leq 50$

• $1 \leq$ grid[i][j] $\leq n \cdot n$

• For all x such that $1 \leq$ x $\leq n \cdot n$, there exists exactly one x that is not equal to any value in grid

• For all x such that $1 \leq$ x $\leq n \cdot n$, there exists exactly one x that is equal to exactly $2$ values in grid

• For all x such that $1 \leq$ x $\leq n \cdot n$ except two of them, there exists exactly one pair i, j such that $0 \leq$ i, j $\leq n - 1$ and grid[i][j] == x

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.