Number Challenge program...

Code:

#include <fstream.h>
#include <iomanip.h>
#include <iostream.h>

#define UNDEFINED 17

/* Format: Rows, columns, possibilities. */
unsigned short int array[16][16][18];

bool IsPossibility(unsigned short int, unsigned short int, unsigned short int);
void Load();
void CheckPossibility();
void DisplayChallenge();
void Step();

int main()
{
	char selection;
		
	Load();
	do
	{
		cout << "? ";
		cin >> selection;

		switch (selection)
		{
			case 'r' : Step();
					   break;
			case 'c' : Load();
					   break;
			case 'd' : DisplayChallenge();
					   break;
			case 'p' : CheckPossibility();
		}
	} while (selection != 'e');

	return 0;
}

bool IsPossibility(unsigned short int column, unsigned short int row, unsigned short int test)
{	
	for (unsigned short int i = 4 * (column / 4); i < 4 * (column / 4) + 4; ++i)
		for (unsigned short int j = 4 * (row / 4); j < 4 * (row / 4) + 4; ++j)
			if (array[j][i][0] == test)
				return false;

	if (column == row)
		for (unsigned short int k = 0; k <= 15; ++k)
			if (array[k][k][0] == test)
				return false;
	else if (column == 15 - row)
		for (unsigned short int k = 0; k <= 15; ++k)
			if (array[k][15 - k][0] == test)
				return false;

	for (unsigned short int l = 0; l <= 16; ++l)
		if (array[l][column][0] == test || array[row][l][0] == test)
			return false;

	return true;
}

void CheckPossibility()
{
	char letter;
	unsigned short int number;
	
	cin >> letter >> number;
	letter -= 'A'; --number;
	if (array[number][letter][0] != UNDEFINED)
		cout << setw(4) << array[number][letter][0];
	else
		for (unsigned short int i = 1; i <= 16; ++i)
			if (IsPossibility(letter, number, i))
				cout << setw(4) << i;
	cout << endl;
}

void DisplayChallenge()
{
	cout << setw(4) << " ";
	for (unsigned short int i = 0; i <= 16; ++i)
	{
		for (unsigned short int j = 0; j <= 16; ++j)
			if (i == 0) cout << setw(4) << char(j + 65);
			else if (j == 0) cout << setw(4) << i;
			else
				if (array[i - 1][j - 1][0] == UNDEFINED) cout << setw(4) << " ";
				else cout << setw(4) << array[i - 1][j - 1][0];
		cout << endl;
	}
}

void Load()
{
	ifstream fin("Puzzle.txt");

	for (int i = 0; i <= 15; ++i)
		for (int j = 0; j <= 15; ++j)
			fin >> array[i][j][0];
		
	fin.close();
}

void Step()
{	
	for (int i = 0; i <= 15; ++i)
		for (int j = 0; j <= 15; ++j)
			if (array[i][j][0] == UNDEFINED)
			{
				int numFound = 0;
				for (int k = 0; k <= 16; ++k)
					if (IsPossibility(j,i,k))
					{
						array[i][j][k + 1] = 1;
						++numFound;
					}
				if (numFound == 1)
					for (int l = 0; l <= 16; l++)
						if (array[i][j][l + 1] == 1)
							array[i][j][0] = l;
			}
}

Code:

In 'Puzzle.txt':
17 17 17 13 17 4 12 17 6 17 3 17 17 7 17 16
8 17 17 7 17 16 17 11 17 9 17 17 17 10 4 6
1 5 17 17 7 6 17 17 13 17 12 17 3 9 17 17
17 12 4 17 17 17 15 17 17 17 17 16 1 17 2 14
10 13 3 17 17 1 17 14 9 7 17 17 5 17 17 17
17 4 17 17 5 17 13 17 17 17 17 10 15 17 1 11
2 17 8 1 17 3 17 17 14 17 17 12 17 6 17 13
5 6 16 15 9 11 10 12 2 8 13 1 4 14 3 7
9 17 7 17 6 17 17 13 5 17 11 17 17 4 15 17
17 1 17 17 17 2 17 15 10 17 17 6 17 17 7 9
17 17 11 14 1 17 17 16 12 17 17 8 2 17 17 17
16 17 17 5 17 17 11 17 17 2 15 17 13 17 17 12
17 9 17 17 12 15 17 17 11 16 17 17 17 17 14 17
11 17 17 10 17 17 4 3 15 17 1 17 17 17 8 5
17 17 5 4 2 17 17 6 17 17 17 3 11 16 17 17
3 17 2 17 17 17 8 17 17 5 14 17 7 15 17 1

The idea is to make a program that will solve for the remaining values (the 17s) with numbers 1 - 16. Each 4x4 square of numbers has each number appearing in it. Each column and row also has all 16 numbers appearing in it. The full diagonals, likewise, have 1-16 taking up all of the room with no repeats.

Any ideas on what I may be doing to screw this up? I have a feeling its something stupid.

snip

Code:

bool IsPossibility(unsigned short int column, unsigned short int row, unsigned short int test)
{	
	for (unsigned short int i = 4 * (column / 4); i < 4 * (column / 4) + 4; ++i)
		for (unsigned short int j = 4 * (row / 4); j < 4 * (row / 4) + 4; ++j)
			if (array[j][0] == test)
				return false;

hmmm look at the if statement
array has 3 indexes, not 2