-
Notifications
You must be signed in to change notification settings - Fork 2
/
algorithm.go
157 lines (139 loc) · 3.05 KB
/
algorithm.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
package main
func KMP(text, pattern string) int {
n, m := len(text), len(pattern)
if m == 0 {
return 0
}
if n < m {
return -1
}
// Compute LPS array
lps := make([]int, m)
i, j := 1, 0
for i < m {
if pattern[i] == pattern[j] {
j++
lps[i] = j
i++
} else if j > 0 {
j = lps[j-1]
} else {
lps[i] = 0
i++
}
}
// Perform string matching
i, j = 0, 0
for i < n {
if pattern[j] == text[i] {
i++
j++
if j == m {
return i - j
}
} else if j > 0 {
j = lps[j-1]
} else {
i++
}
}
return -1
}
func BM(text, pattern string) int {
n := len(text)
m := len(pattern)
if m == 0 {
return 0
}
// build the bad character table
bc := make(map[rune]int)
for i := 0; i < m-1; i++ {
bc[rune(pattern[i])] = m - i - 1
}
// build the good suffix table
suffixes := make([]int, m)
f := make([]int, m+1)
var j int
var k int
for i := m - 1; i >= 0; i-- {
for j > 0 && pattern[j-1] != pattern[i] {
suffixes[j-1] = k
j = f[j]
}
if j > 0 && pattern[j-1] == pattern[i] {
j--
} else {
k = i
}
suffixes[i] = k
f[i] = j
}
for j > 0 {
suffixes[j-1] = k
j = f[j]
}
// search the pattern in the text
i := m - 1
j = m - 1
for i < n && j >= 0 {
if text[i] == pattern[j] {
i--
j--
} else {
shift := max(bc[rune(text[i])], suffixes[j])
i += m - min(j, 1+shift)
j = m - 1
}
}
if j < 0 {
return i + 1
}
return -1
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func min(a, b int) int {
if a < b {
return a
}
return b
}
func levenshteinDistance(s, t string) int {
n := len(s)
m := len(t)
if n == 0 {
return m
}
if m == 0 {
return n
}
// Create a matrix to store the distances between prefixes of s and t
// The (i,j)th entry of the matrix represents the distance between the first i characters of s and the first j characters of t
matrix := make([][]int, n+1)
for i := range matrix {
matrix[i] = make([]int, m+1)
}
// Initialize the first row and column of the matrix
for i := 0; i <= n; i++ {
matrix[i][0] = i
}
for j := 0; j <= m; j++ {
matrix[0][j] = j
}
// Fill in the rest of the matrix
for i := 1; i <= n; i++ {
for j := 1; j <= m; j++ {
substitutionCost := 1
if s[i-1] == t[j-1] {
substitutionCost = 0
}
matrix[i][j] = min(matrix[i-1][j]+1, min(matrix[i][j-1]+1, matrix[i-1][j-1]+substitutionCost))
}
}
// The distance between s and t is the bottom right entry of the matrix
return matrix[n][m]
}