pyTraceAlphabet

# Trace the alphabet by moving Right, Down, Left and Up through a matrix

a = ["ACRFGHOT",
"BCDEVIQR",
"PXDUKJPQ",
"FYASLOPQ",
"RTVHMNSR",
"YSZVVUTB",
"MDYXWUPV",
"REWQSDEF"]
rows = len(a)
cols = len(a[0])

letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ."
idx = 0  # position within alphabet
# note . as an end marker

# dict of x,y moves per direction
# where x is column, y is row
# e.g. Right adds 1 to x, y stays same
dirs = {"R": (1, 0), "D": (0, 1), "L": (-1, 0), "U": (0, -1)}

x, y = -1, 0  # start 1 place to left of top left corner

# loop until all alphabet found
while letters[idx] != ".":
    for d in dirs.keys():     # R, D, L, U
        # get moves for a direction
        dx, dy = dirs[d]
        # compute temporary next pos
        dx += x
        dy += y
    # check column and row indexes are not out of bounds
        if -1 < dx < cols and -1 < dy < rows:
            # does this pos hold the next letter?
            if a[dy][dx] == letters[idx]:
                break   # yes, quit inner loop

    print(d, letters[idx]) # show progress

    # confirm good position
    x, y = dx, dy

    # bump idx to next letter
    idx += 1