In a square layout of size $5\;\text{m} \times 5\;\text{m}, 25$ equal sized square platforms of different heights are built. The heights (in metres) of individual platforms are as shown below:
$$\begin{array}{ccccc} 6 & 1 & 2 & 4 & 3 \\ 9 & 5 & 3 & 2 & 8 \\ 7 & 8 & 4 & 6 & 5 \\ 3 & 9 & 5 & 1 & 2 \\ 1 & 7 & 6 & 3 & 9 \end{array}$$
Individuals (all of same height) are seated on these platforms. We say an individual $\text{A}$ can reach an individual $\text{B}$ if all the three following conditions are met:
- $\text{A}$ and $\text{B}$ are in the same row or column
- $\text{A}$ is at a lower height than $\text{B}$
- If there is/are any individuals(s) between $\text{A}$ and $\text{B}$, such Individual(s) must be at a height tower than that of $\text{A}$.
Thus in the table given above, consider the Individual seated at height $8$ on $3$rd row and $2$nd column. He can be reached by four individuals. He can be reached by the individual on his left at height $7$, by the two individuals on his right at heights of $4$ and $6$ and by the individual above at height $5$.
Rows in the layout are numbered from top to bottom and columns are numbered from left to right.
We can find two individuals who cannot be reached by anyone in
- the last row
- the fourth row
- the fourth column
- the middle column