rustgym/leetcode/
_10_regular_expression_matching.rs

1struct Solution;
2
3impl Solution {
4    fn is_match(s: String, p: String) -> bool {
5        let n = s.len();
6        let m = p.len();
7        let s: Vec<char> = s.chars().collect();
8        let p: Vec<char> = p.chars().collect();
9        let mut memo: Vec<Vec<Option<bool>>> = vec![vec![None; m + 1]; n + 1];
10        Self::is_match_dp(n, m, &mut memo, &s, &p)
11    }
12
13    fn is_match_dp(
14        n: usize,
15        m: usize,
16        memo: &mut Vec<Vec<Option<bool>>>,
17        s: &[char],
18        p: &[char],
19    ) -> bool {
20        if let Some(ans) = memo[n][m] {
21            ans
22        } else {
23            let res = if n == 0 && m == 0 {
24                true
25            } else if n != 0 && m == 0 {
26                false
27            } else if n == 0 && m != 0 {
28                if p[m - 1] == '*' {
29                    Self::is_match_dp(n, m - 2, memo, s, p)
30                } else {
31                    false
32                }
33            } else {
34                if s[n - 1] == p[m - 1] {
35                    Self::is_match_dp(n - 1, m - 1, memo, s, p)
36                } else {
37                    match p[m - 1] {
38                        '*' => match p[m - 2] {
39                            '*' => false,
40                            '.' => {
41                                Self::is_match_dp(n - 1, m, memo, s, p)
42                                    || Self::is_match_dp(n, m - 2, memo, s, p)
43                            }
44                            _ => {
45                                if s[n - 1] != p[m - 2] {
46                                    Self::is_match_dp(n, m - 2, memo, s, p)
47                                } else {
48                                    Self::is_match_dp(n - 1, m, memo, s, p)
49                                        || Self::is_match_dp(n, m - 2, memo, s, p)
50                                }
51                            }
52                        },
53                        '.' => Self::is_match_dp(n - 1, m - 1, memo, s, p),
54                        _ => false,
55                    }
56                }
57            };
58
59            memo[n][m] = Some(res);
60            res
61        }
62    }
63}
64
65#[test]
66fn test() {
67    let s = "aa".to_string();
68    let p = "a".to_string();
69    let res = false;
70    assert_eq!(Solution::is_match(s, p), res);
71    let s = "aa".to_string();
72    let p = "a*".to_string();
73    let res = true;
74    assert_eq!(Solution::is_match(s, p), res);
75    let s = "ab".to_string();
76    let p = ".*".to_string();
77    let res = true;
78    assert_eq!(Solution::is_match(s, p), res);
79    let s = "aab".to_string();
80    let p = "c*a*b".to_string();
81    let res = true;
82    assert_eq!(Solution::is_match(s, p), res);
83    let s = "mississippi".to_string();
84    let p = "mis*is*p*.".to_string();
85    let res = false;
86    assert_eq!(Solution::is_match(s, p), res);
87}
rustgym/leetcode/_10_regular_expression_matching.rs

rustgym/leetcode/
_10_regular_expression_matching.rs
