Task: Knight's tour
C#: using System;
using System.Collections.Generic;

namespace prog
{
	class MainClass
	{	
		const int N = 8;
		
		readonly static int[,] moves = { {+1,-2},{+2,-1},{+2,+1},{+1,+2},
			                         {-1,+2},{-2,+1},{-2,-1},{-1,-2} };
		struct ListMoves
		{
			public int x, y;			
			public ListMoves( int _x, int _y ) { x = _x; y = _y; }
		}		
		
		public static void Main (string[] args)
		{
			int[,] board = new int[N,N];
			board.Initialize();
			
			int x = 0,						
			    y = 0;
			
			List<ListMoves> list = new List<ListMoves>(N*N);
			list.Add( new ListMoves(x,y) );
						
			do
			{								
				if ( Move_Possible( board, x, y ) )
				{										
					int move = board[x,y];					
					board[x,y]++;
					x += moves[move,0];
					y += moves[move,1];			
					list.Add( new ListMoves(x,y) );							
				}
				else
				{					
					if ( board[x,y] >= 8 )
					{						
						board[x,y] = 0;																
						list.RemoveAt(list.Count-1);						
						if ( list.Count == 0 )
						{
							Console.WriteLine( "No solution found." );
							return;
						}		
						x = list[list.Count-1].x;
						y = list[list.Count-1].y;						
					}
					board[x,y]++;
				}				
			}
			while( list.Count < N*N );
			
			int last_x = list[0].x,
			    last_y = list[0].y;
			string letters = "ABCDEFGH";
			for( int i=1; i<list.Count; i++ )
			{				
				Console.WriteLine( string.Format("{0,2}:  ", i) + letters[last_x] + (last_y+1) + " - " + letters[list[i].x] + (list[i].y+1) );
				
				last_x = list[i].x;
				last_y = list[i].y;
			}
		}
		
		static bool Move_Possible( int[,] board, int cur_x, int cur_y )
		{			
			if ( board[cur_x,cur_y] >= 8 ) 
				return false;
			
			int new_x = cur_x + moves[board[cur_x,cur_y],0],
			    new_y = cur_y + moves[board[cur_x,cur_y],1];
			
			if ( new_x >= 0 && new_x < N && new_y >= 0 && new_y < N && board[new_x,new_y] == 0 )
				return true;
			
			return false;
		}
	}
}

C++: #include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <tuple>
#include <algorithm>
using namespace std;

template<int N = 8>
class Board 
{
public:
    array<pair<int, int>, 8> moves;
    array<array<int, N>, N> data;

    Board() 
    {
        moves[0] = make_pair(2, 1);
        moves[1] = make_pair(1, 2);
        moves[2] = make_pair(-1, 2);
        moves[3] = make_pair(-2, 1);
        moves[4] = make_pair(-2, -1);
        moves[5] = make_pair(-1, -2);
        moves[6] = make_pair(1, -2);
        moves[7] = make_pair(2, -1);
    }

    array<int, 8> sortMoves(int x, int y) const 
    {
        array<tuple<int, int>, 8> counts;
        for(int i = 0; i < 8; ++i) 
        {
            int dx = get<0>(moves[i]);
            int dy = get<1>(moves[i]);

            int c = 0;
            for(int j = 0; j < 8; ++j) 
            {
                int x2 = x + dx + get<0>(moves[j]);
                int y2 = y + dy + get<1>(moves[j]);

                if (x2 < 0 || x2 >= N || y2 < 0 || y2 >= N)
                    continue;
                if(data[y2][x2] != 0)
                    continue;

                c++;
            }

            counts[i] = make_tuple(c, i);
        }

        
        random_shuffle(counts.begin(), counts.end());

        
        sort(counts.begin(), counts.end());

        array<int, 8> out;
        for(int i = 0; i < 8; ++i)
            out[i] = get<1>(counts[i]);
        return out;
    }

    void solve(string start) 
    {
        for(int v = 0; v < N; ++v)
            for(int u = 0; u < N; ++u)
                data[v][u] = 0;

        int x0 = start[0] - 'a';
        int y0 = N - (start[1] - '0');
        data[y0][x0] = 1;

        array<tuple<int, int, int, array<int, 8>>, N*N> order;
        order[0] = make_tuple(x0, y0, 0, sortMoves(x0, y0));

        int n = 0;
        while(n < N*N-1) 
        {
            int x = get<0>(order[n]);
            int y = get<1>(order[n]);

            bool ok = false;
            for(int i = get<2>(order[n]); i < 8; ++i) 
            {
                int dx = moves[get<3>(order[n])[i]].first;
                int dy = moves[get<3>(order[n])[i]].second;

                if(x+dx < 0 || x+dx >= N || y+dy < 0 || y+dy >= N)
                    continue;
                if(data[y + dy][x + dx] != 0) 
                    continue;

                get<2>(order[n]) = i + 1;
                ++n;
                data[y+dy][x+dx] = n + 1;
                order[n] = make_tuple(x+dx, y+dy, 0, sortMoves(x+dx, y+dy));
                ok = true;
                break;
            }

            if(!ok) 
            {
                data[y][x] = 0;
                --n;
            }
        }
    }

    template<int N>
    friend ostream& operator<<(ostream &out, const Board<N> &b);
};

template<int N>
ostream& operator<<(ostream &out, const Board<N> &b) 
{
    for (int v = 0; v < N; ++v) 
    {
        for (int u = 0; u < N; ++u) 
        {
            if (u != 0) out << ",";
            out << setw(3) << b.data[v][u];
        }
        out << endl;
    }
    return out;
}

int main() 
{
    Board<5> b1;
    b1.solve("c3");
    cout << b1 << endl;

    Board<8> b2;
    b2.solve("b5");
    cout << b2 << endl;

    Board<31> b3; 
    b3.solve("a1");
    cout << b3 << endl;
    return 0;
}