dsalgo 0.3.10

A package for Datastructures and Algorithms.
Documentation 
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
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180

pub fn sa_is(mut a: Vec<usize>) -> Vec<usize> {
    let m = *a.iter().min().unwrap();

    for x in a.iter_mut() {
        *x = *x - m + 1;
    }

    a.push(0);

    let n = a.len();

    let m = a.iter().max().unwrap() + 1;

    let mut is_s = vec![true; n];

    let mut is_lms = vec![false; n];

    let mut lms = Vec::with_capacity(n);

    for i in (1..n).rev() {
        is_s[i - 1] = if a[i - 1] == a[i] { is_s[i] } else { a[i - 1] < a[i] };

        is_lms[i] = !is_s[i - 1] && is_s[i];

        if is_lms[i] {
            lms.push(i);
        }
    }

    lms.reverse();

    let mut arg_l = vec![0; m];

    let mut arg_r = vec![0; m];

    for &x in a.iter() {
        arg_r[x] += 1;

        if x < m - 1 {
            arg_l[x + 1] += 1;
        }
    }

    for i in 0..m - 1 {
        arg_r[i + 1] += arg_r[i];

        arg_l[i + 1] += arg_l[i];
    }

    let induce = |lms: &Vec<usize>| -> Vec<usize> {
        let mut sa = vec![n; n];

        let mut arg = arg_r.clone();

        for &i in lms.iter().rev() {
            arg[a[i]] -= 1;

            sa[arg[a[i]]] = i;
        }

        let mut arg = arg_l.clone();

        for i in 0..n {
            if sa[i] == n || sa[i] == 0 {
                continue;
            }

            let i = sa[i] - 1;

            if !is_s[i] {
                sa[arg[a[i]]] = i;

                arg[a[i]] += 1;
            }
        }

        let mut arg = arg_r.clone();

        for i in (0..n).rev() {
            if sa[i] == n || sa[i] == 0 {
                continue;
            }

            let i = sa[i] - 1;

            if is_s[i] {
                arg[a[i]] -= 1;

                sa[arg[a[i]]] = i;
            }
        }

        sa
    };

    let l = lms.len();

    let lms_idx =
        induce(&lms).into_iter().filter(|&i| is_lms[i]).collect::<Vec<_>>();

    let mut rank = vec![n; n];

    let mut r = 0;

    rank[n - 1] = r;

    for i in 0..l - 1 {
        let j = lms_idx[i];

        let k = lms_idx[i + 1];

        for d in 0..n {
            if a[j + d] != a[k + d] {
                r += 1;

                break;
            }

            if d > 0 && is_lms[j + d] {
                if !is_lms[k + d] {
                    r += 1;
                }

                break;
            }
        }

        rank[k] = r;
    }

    rank = rank.into_iter().filter(|&x| x != n).collect();

    let mut lms_order: Vec<usize> = Vec::new();

    if r == l - 1 {
        lms_order.resize(l, n);

        for i in 0..l {
            lms_order[rank[i]] = i;
        }
    } else {
        lms_order = sa_is(rank);
    }

    lms = lms_order.iter().map(|&i| lms[i]).collect();

    let sa = induce(&lms);

    sa[1..].to_vec()
}

pub fn from_str(s: &str) -> Vec<usize> {
    sa_is(s.as_bytes().iter().map(|&x| x as usize).collect())
}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn suffix_array() {
        let cases = vec![
            (
                vec![1, 1, 0, 0, 3, 3, 0, 0, 3, 3, 0, 0, 2, 2, 0, 0],
                vec![15, 14, 10, 6, 2, 11, 7, 3, 1, 0, 13, 12, 9, 5, 8, 4],
            ),
            (
                vec![1, 0, 3, 3, 0, 3, 3, 0, 2, 2, 0],
                vec![10, 7, 4, 1, 0, 9, 8, 6, 3, 5, 2],
            ),
        ];

        for (s, ans) in cases {
            assert_eq!(sa_is(s), ans);
        }
    }
}