2D Arrays

Classwork/Homework:

Implement the following algorithm to construct magic n × n squares; it works only if n is odd.Set row = n – 1, column = n / 2.
For k = 1 … n * n
Place k at [row][column].
Increment row and column.
If the row or column is n, replace it with 0.
If the element at [row][column] has already been filled
{ Set row and column to their previous values.
Decrement row.}

Here is the 5 × 5 square that you get if you follow this method:

Write a program, MagicNSquare_YI.java whose input is the number n and whose output is the magic square of order n if n is odd. Include the code to check the new array is in fact a Magic Square. Display the sum of the columns, rows and diagonals.
(Financial tsunami) Banks lend money to each other. In tough economic times, if a bank goes bankrupt, it may not be able to pay back the loan. A bank’s total assets are its current balance plus its loans to other banks. The diagram in the figure below shows five banks. The banks’ current balances are 25, 125, 175, 75, and 181 million dollars, respectively. The arrow from node 1 to node 2 indicates that bank 1 lends 40 million dollars to bank 2.
If a bank’s total assets are under a certain limit, the bank is unsafe. The money it borrowed cannot be returned to the lender, and the lender cannot count the loan in its total assets. Consequently, the lender may also be unsafe, if its total assets are under the limit. Write a program, BankFinancing_YI.java to find all the unsafe banks. Your program reads the input as follows. It first reads two integers n and limit, where n indicates the number of banks and limit is the minimum total assets for keeping a bank safe. It then reads n lines that describe the information for n banks with IDs from 0 to n-1.
The first number in the line is the bank’s balance, the second number indicates the number of banks that borrowed money from the bank, and the rest are pairs of two numbers. Each pair describes a borrower. The first number in the pair is the borrower’s ID and the second is the amount borrowed. For example, the input for the five banks in the figure is as follows (note that the limit is 201):
```
5 201
25 2 1 100.5 4 320.5
125 2 2 40 3 85
175 2 0 125 3 75
75 1 0 125
181 1 2 125
```
The total assets of bank 3 are (75 + 125), which is under 201, so bank 3 is unsafe. After bank 3 becomes unsafe, the total assets of bank 1 fall below (125 + 40). Thus, bank 1 is also unsafe. The output of the program should be
```
Unsafe banks are 3 1
```
(Hint: Use a two-dimensional array borrowers to represent loans. borrowers[i][j] indicates the loan that bank i loans to bank j. Once bank j becomes unsafe, borrowers[i][j] should be set to 0.)