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sudoku_test

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+.6....28.
+...419..5
+....8..79

sudoku_test_solved

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+345286179

sudokusolv.py

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+"""
+9x9 Sudoku solver
+"""
+
+import curses
+import time
+
+row = ['.'] * 9
+puzzle = [row[:] for i in range(0,9)]
+
+# test sudoku from http://upload.wikimedia.org/wikipedia/commons/f/ff/Sudoku-by-L2G-20050714.svg
+# answer at http://upload.wikimedia.org/wikipedia/commons/3/31/Sudoku-by-L2G-20050714_solution.svg
+# puzzle[0][0] = -5
+# puzzle[0][1] = -3
+# puzzle[0][4] = -7
+# puzzle[1][0] = -6
+# puzzle[1][3] = -1
+# puzzle[1][4] = -9
+# puzzle[1][5] = -5
+# puzzle[2][1] = -9
+# puzzle[2][2] = -8
+# puzzle[2][7] = -6
+# puzzle[3][0] = -8
+# puzzle[3][4] = -6
+# puzzle[3][8] = -3
+# puzzle[4][0] = -4
+# puzzle[4][3] = -8
+# puzzle[4][5] = -3
+# puzzle[4][8] = -1
+# puzzle[5][0] = -7
+# puzzle[5][4] = -2
+# puzzle[5][8] = -6
+# puzzle[6][1] = -6
+# puzzle[6][6] = -2
+# puzzle[6][7] = -8
+# puzzle[7][3] = -4
+# puzzle[7][4] = -1
+# puzzle[7][5] = -9
+# puzzle[7][8] = -5
+# puzzle[8][4] = -8
+# puzzle[8][7] = -7
+# puzzle[8][8] = -9
+
+# UI, setup puzzle from file
+def initpuzzle (file, puzle = []):
+    """
+    Setups the sudoku puzzle to solve from certain text file
+    """
+    f = open(file, 'r')
+    for r, row in enumerate(f):
+        for c, cell in enumerate(row):
+            if cell == '\n': continue
+            try:
+                int(cell)
+                puzzle[r][c] = -1 * int(cell)
+            except Exception as e:
+                puzzle[r][c] = '.'
+    f.close()
+
+# UI, print a puzzle sample. Also may print to file
+def printpuzzle (puzle = [], f = None):
+    """
+    Prints puzzle in current status, using curses
+
+    It may print in to a file too
+    """
+    global scr
+    for r, row in enumerate(puzzle):
+        for c, cell in enumerate(row):
+            if cell == '.':
+                scr.addstr(r*3, c*3, str(cell))
+                if f != None: f.write(str(cell))
+            else:
+                scr.addstr(r*3, c*3, str(abs(int(cell))))
+                if f != None: f.write(str(abs(int(cell))))
+        if f != None: f.write('\n')
+    scr.refresh()
+    time.sleep(0.0)
+
+# UI, main routine, calling certain sudoku solver routine
+def solvesudoku (file, puzle = []) :
+    """
+    Main routine which seeks the sudoku solving.
+
+    Uses curses to print in screen
+    """
+    global scr
+    initpuzzle(file, puzzle)
+    printpuzzle(puzle)
+    r = nextsquare((0,0), puzle)
+    f = open(file + "_solved", 'w')
+    if r == -1:
+        scr.addstr(25, 0, "No solution found!")
+        f.write("No solution found!\n")
+        printpuzzle(puzle)
+    else:
+        printpuzzle(puzle, f)
+    f.close()
+    c = scr.getch()
+
+# Brute force recursive algorithm
+def nextsquare ((x, y), puzle = []):
+    """
+    Recursive algorithm to solve sudoku puzzle, via brute-force
+    """
+    if (x, y) == (-1, -1):
+        return 1
+
+    if puzle[x][y] == '.':
+        for val in range(1, 10):
+            valid = validate((x, y), val, puzle)
+            if valid:
+                puzle[x][y] = val
+                printpuzzle(puzle)
+                r = nextsquare(nextcoords(x, y), puzle)
+                if r == 1:
+                    return 1
+
+        puzle[x][y] = '.'
+        printpuzzle(puzle)
+        return -1
+
+    elif puzle[x][y] < 0:
+        r = nextsquare(nextcoords(x, y), puzle)
+        if r == 1:
+            return 1
+
+    return -1
+
+
+# Brute force recursive algorithm, get next coordinates in recursiveness
+def nextcoords (x = 0, y = 0):
+    """
+    Gets the next pair of coordinates for the brute force recursive algorithm
+    """
+    y = y + 1
+    if y == 9:
+        y = 0
+        x = x + 1
+        if x == 9:
+            return (-1, -1)
+
+    return (x, y)
+
+# Sudoku solver, validate new value in certain coordinates
+def validate ((x, y), val, puzle = []):
+    """
+    Given some value at certain coordinates, validates according to sudoku rules
+    """
+    # valida renglones
+    for v in puzle[x]:
+        if v == '.': continue
+        if abs(int(v)) == val:
+            return False
+
+    # valida columnas
+    ycol = [row[y] for row in puzle]
+    for v in [cv for cv in ycol]:
+        if v == '.': continue
+        if abs(int(v)) == val:
+            return False
+
+    # valida cuadrantes
+    X = x / 3 # cuadrante en X
+    Y = y / 3 # cuadrante en Y
+
+    for i in range(1,10):
+        if i / 3 != X: continue
+        for j in range(1,10):
+            if j / 3 != Y: continue
+            v = puzle[i][j]
+            if v == '.': continue
+            if abs(int(v)) == val:
+                return False
+
+    return True
+
+# Rutina principal
+if __name__ == '__main__':
+    global scr
+
+    scr = curses.initscr()
+    curses.noecho()
+    curses.cbreak()
+    curses.start_color()
+    curses.curs_set(0)
+    scr.keypad(1)
+
+    try:
+        solvesudoku('sudoku_test', puzzle[:])
+    except KeyboardInterrupt:
+        pass
+    except Exception as e:
+        scr.addstr("Error! " + str(e))
+        scr.refresh()
+        scr.getch()
+        pass
+
+    curses.nocbreak()
+    curses.echo()
+    curses.endwin()