You are given a $2$D integer matrix grid of size $n \times m$.

Traverse the grid in a zigzag order according to the following process:

• Start at the top left cell of the grid.

• Move from left to right on even indexed rows (starting with row $0$).

• Move from right to left on odd indexed rows.

• Alternate directions for each consecutive row until all elements have been traversed.

• Include every alternating element in the result, starting by including the very first cell visited.

Return an array of integers containing the collected values in the order they were visited.

Constraints:

• $2 \leq n ==$ grid.length $\leq 50$

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

• $1 \leq$ grid[i][j] $\leq 2500$

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.