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# txt = "zzzzzzzzzabczzzzzzzzzz"
# pat = "abczzzabc"
# m = len(pat)
# n = len(txt)
# R = [[m for __ in range(m)] for _ in range(0, 26)]
# good_suffix = [0 for _ in range(0, m+1)]
def alpha_number(char):
return int(char)
def reverse(string):
return string[::-1]
def compare(string, i, end):
for j in range(end):
if i+j == end or string[i+j] != string[j]:
return j
def gusfield(string):
z = [0 for _ in string]
z[0] = len(string)
r = 0
l = 0
for i in range(1, len(string)):
if i == 1: # base case
z[1] = compare(string, i, len(string))
if z[1] > 0:
r = z[1] + 1
l = 1
elif i > r: # Case 1
z[i] = compare(string, i, len(string))
if z[i] > 0:
q = i + z[i]
r = q - 1
l = i
elif i <= r: # Case 2
if z[i-l] < r-i: # Case 2a
z[i] = z[i-l]
else: # Case 2b
q = compare(string, i, len(string))
z[i] = q
r = q
l = i
return z
def gen_jump_table(pat):
m = len(pat)
R = [[-1 for __ in range(m)] for _ in range(0, 2)]
for j in range(m):
for i in range(j+1):
R[alpha_number(pat[i])][j] = i
return R
def gen_z_suffix(pat):
return reverse(gusfield(reverse(pat)))+[0]
# print(list(pat))
# print(R)
# print(Z)
def gen_good_suffix(pat, Z):
m = len(pat)
good_suffix = [0 for _ in range(0, m + 1)]
for i in range(m):
j = m - Z[i]
good_suffix[j] = i+1
return good_suffix
# print("g", good_suffix)
def gen_matched_prefix(pat):
m = len(pat)
matched_prefix = gusfield(pat)+[0]
for i in range(m-1, -1, -1):
matched_prefix[i] = max(matched_prefix[i], matched_prefix[i+1])
return matched_prefix
def preprocess(pat):
R = gen_jump_table(pat)
Z = gen_z_suffix(pat)
good_suffix = gen_good_suffix(pat, Z)
matched_prefix = gen_matched_prefix(pat)
return R, good_suffix, matched_prefix
def boyer_moore(pat, txt):
R, good_suffix, matched_prefix = preprocess(pat)
m = len(pat)
n = len(txt)
j = 0
occurrence = 0
start = None
stop = None
galil_index = -1
comps = 0
print("="*15)
print(6*" " + txt)
while j <= n-m:
matches = 0
for i in range(m-1, -1, -1):
# if galil_index == j and start <= i < stop:
# print("pee")
# i = max(start + 1, 1)
# continue
print(f"{j=:02} {' ' * j}", end="")
for x in range(len(pat)):
if x == i:
print(pat[x].upper(), end="")
else:
print(pat[x], end="")
print()
match = pat[i] == txt[j+i]
comps += 1
if match:
matches += 1
if matches == m:
good_suffix_shift = m - matched_prefix[1]
j += good_suffix_shift
i = m-1
occurrence += 1
break
else:
mismatched = txt[j+i]
bad_char_shift = i-R[alpha_number(mismatched)][i]
good_suffix_shift = 1
if good_suffix[i+1] > 0:
good_suffix_shift = m - good_suffix[i+1]
start = good_suffix[i+1] - m + i
stop = good_suffix[i+1]
next_galil = j+1
elif good_suffix[i+1] == 0:
good_suffix_shift = m - matched_prefix[i+1]
start = 1
stop = matched_prefix[i+1]
next_galil = j+1
elif matches == m:
print(f"Match at {j}")
good_suffix_shift = m - matched_prefix[1]
# print(start, stop)
j += max(good_suffix_shift, bad_char_shift)
# print(good_suffix_shift, bad_char_shift)
if good_suffix_shift >= bad_char_shift:
print("good suff", good_suffix_shift)
else:
print("bad char", bad_char_shift)
print(i)
if good_suffix[i+1] >= 0 and good_suffix_shift >= bad_char_shift:
galil_index = j
break
print(f"It found {occurrence} occurences.")
print(f"\n {list(range(m))}")
for i, a in enumerate(R):
print(chr(i+97), a)
print(f"{comps} comparisons.")
boyer_moore("111101111111111", "101010111010010101110111010101110100101011101101111011111111111101110111010101110100101011101101101110111010101110100101011101101101110110000110101011101001010111011011011101100001010101110100101011101110101011101001010111011011011101110101011101001010111011011011101110101011101001010111011011011101100001101010111010010101110110110111011000010111011111011101110110101110110101101100000001011001010101010101110111110111011101101011101101011011000000010110010101010101000010111011111011101110110101110110101101100000001011001010101010100001011101111101110111011010111011010110110000000101100101010101010101011101001010111011011011101100001011101111101110111011010101110100101011101101101110110000101110111110101010111010010101110110110111011000010111011101010111010010101110110110111011000010111010101110100101011101101101010101110100101011101101101110110000101110111110111011101101011101101011011000000010110010101010101111011000010111011111011101110110101110110101101100000001011001010101010110111110111011101101011101101011011000000010110010101010101111011101110110101110110101101100000001011001010101010111101110110101110110101101100000001011001010101010110101110110101101100000001011001010101010110110111011000010101011101001010111011101010111010010101110110110111011101010111010010101110110110111011101010111010010101110110110111011000011010101110100101011101101101110110000101110111110111011101101011101101011011000000010110010101010101011101111101110111011010111011010110110000000101100101010101010000101110111110111011101101011101101011011000000010110010101010101000010111011111011101110110101110110101101100000001011001010101010101010111010010101110110110111011000010111011111011101110110101011101001010111011011011101100001011101111101010101110100101011101101101110110000101110111010101110100101011101101101110110000101110101011101001010111011011010101011101001010111011011011101100001011101111101110111011010111011010110110000000101100101010101011110110000101110111110111011101101011101101011011000000010110010101010101101111101110111011010111011010110110000000101100101010101011110111011101101011101101011011000000010110010101010101111011101101011101101011011000000010110010101010101101011101101011011000000010110010101010101101101110110000101110111110111011101101011101101011011000000010110010101010101101110111110111011101101011101101011011000000010110010101010101101110111110111011101101011101101011011000000010110010101010101011101111101110111011010111011010110110000000101100101010101010000101110111110111011101101011101101011011000000010110010101010101000010111011111011101110110101110110101101100000001011001010101010101010111101111111111111010010101110110110111011000010111011111011101110110101011101001010111011011011101100001011101111101010101110100101011101101101110110000101110111010101110100101011101101101110110000101110101011101001010111011011010101011101001010111011011011101100001011101111101110111011010111011010110110000000101100101010101011110110000101110111110111011101101011101101011011000000010110010101010101101111101110111011010111011010110110000000101100101010101011110111011101101011101101011011000000010110010101010101111011101101011101101011011000000010110010101010101101011101101011011000000010110010101010101101101110110000101110111110111011101101011101101011011000000010110010101010101")
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