Initial commit

knightstour.adb

@@ -0,0 +1,123 @@
+with Ada.Text_IO; use Ada.Text_IO;
+with ada.Integer_Text_IO; use Ada.Integer_Text_IO;
+with ada.Float_Text_IO; use ada.Float_Text_IO;
+procedure knightstour is
+    --Initiate a 2d array with an unknown subrange and other more simple variables
+    type board is array (natural range <>, natural range <>) of integer;
+    -- arrays a and b are all 8 (x,y) movements a knight can make 
+    a: array (1..8) of integer := (2,1,-1,-2,-2,-1,1,2);
+    b: array (1..8) of integer := (1,2,2,1,-1,-2,-2,-1);
+    size : integer := 5;
+    n : integer := 1;
+    xpos, ypos : integer;
+    q : boolean;
+    
+    --Recursive procedure that does the solving portion of the algorithm
+    procedure try(i, x, y: in integer; q: out boolean; h: in out board) is
+        k, u, v : integer;
+        q1 : boolean;
+    begin
+    
+        k := 0;
+        
+        --Loops until all knights movement(k) kas been attempted or a knights move works
+        --Loop calls the try procedure resulting in the recursive part of this algorithm 
+        loop
+
+            k := k+1;
+            q1 := false;
+            u := x+(a(k));
+            v := y+(b(k));
+            
+            --Checks if u and v are within the size of the chess board
+            if (u in 1..size) and (v in 1..size) then
+                if h(u,v) = 0 then
+                    h(u,v) := i;
+                    --If the number of calls to try is less than all board spaces
+                    --the try procedure is called again
+                    if i < n then
+                        try(i+1,u,v,q1,h);
+                        if not q1 then
+                            h(u,v) := 0;
+                        end if;
+                    else 
+                        q1 := true;
+                    end if;
+                    
+                end if;
+            
+            end if;
+        
+            exit when q1 or k=8;
+        end loop;
+        q := q1;
+    end try;
+    
+    --Procedure that draws out the board after calling the try procedure
+    procedure makeBoard(size, xpos, ypos: in out integer) is
+        --Given the input provided by the user a 2d array the 
+        --length and width of the chess board is created
+        h : board(1..size, 1..size);
+        outfp : file_type;
+        two: integer := 2;
+    begin
+    
+        create(outfp, out_file, "tour.txt");
+    
+        --Board array is filled with 0's
+        for i in 1..size loop
+            for j in 1..size loop
+                h(i,j) := 0;
+            end loop;
+        end loop;
+        
+        --try procedure is called and starting position is set in board array
+        h(xpos,ypos) := 1;
+        try(two, xpos, ypos, q, h);
+        
+        --After the try procedure is finished running, it is checked if the board array
+        --has any zeros, if it does this means the algorithm didn't work correctly
+        for i in 1..size loop
+            for j in 1..size loop
+                if h(i,j) = 0 then
+                    q := false;
+                end if;
+            end loop;
+        end loop;
+        
+        --If the knights tour is possible the entire board is printed out with all steps
+        --If not "No solution" is printed out instead
+        if q then
+            for i in 1..size loop
+                for j in 1..size loop
+                    put(h(i,j));
+                    put(outfp, h(i,j));
+                end loop;
+                new_line;
+            end loop;     
+        end if; 
+        
+        if not q then 
+            put_line("No Solution. :(");
+            put(outfp, "No Solution. :(");
+        end if;
+        
+         close(outfp);
+        
+        end makeBoard;
+
+--Starting procedure
+begin
+    
+    --Asks for and receives input to figure out the size of the chess board
+    --and the starting position of the knight
+    --Also calls the makeboard procedure
+    Put("Input size of chess board (Between 5 - 10) :");
+    Get(size);
+    Put("Start Position: x y ");
+    Get(xpos);
+    Get(ypos);
+    n := size*size;
+    makeBoard(size, xpos, ypos);
+ 
+end knightstour;

makefile

@@ -0,0 +1,5 @@
+main: knightstour.adb
+	gnatmake knightstour.adb
+
+clean:
+	rm knightstour knightstour.ali knightstour.o tour.txt