2264. Largest 3-Same-Digit Number in String Easy

1/**
2 * [2264] Largest 3-Same-Digit Number in String
3 *
4 * You are given a string num representing a large integer. An integer is good if it meets the following conditions:
5 * 
6 * It is a substring of num with length 3.
7 * It consists of only one unique digit.
8 * 
9 * Return the maximum good integer as a string or an empty string "" if no such integer exists.
10 * Note:
11 * 
12 * A substring is a contiguous sequence of characters within a string.
13 * There may be leading zeroes in num or a good integer.
14 * 
15 *  
16 * Example 1:
17 * 
18 * Input: num = "6<u>777</u>133339"
19 * Output: "777"
20 * Explanation: There are two distinct good integers: "777" and "333".
21 * "777" is the largest, so we return "777".
22 * 
23 * Example 2:
24 * 
25 * Input: num = "23<u>000</u>19"
26 * Output: "000"
27 * Explanation: "000" is the only good integer.
28 * 
29 * Example 3:
30 * 
31 * Input: num = "42352338"
32 * Output: ""
33 * Explanation: No substring of length 3 consists of only one unique digit. Therefore, there are no good integers.
34 * 
35 *  
36 * Constraints:
37 * 
38 * 3 <= num.length <= 1000
39 * num only consists of digits.
40 * 
41 */
42pub struct Solution {}
43
44// problem: https://leetcode.com/problems/largest-3-same-digit-number-in-string/
45// discuss: https://leetcode.com/problems/largest-3-same-digit-number-in-string/discuss/?currentPage=1&orderBy=most_votes&query=
46
47// submission codes start here
48
49impl Solution {
50    pub fn largest_good_integer(num: String) -> String {
51        let chs: Vec<char> = num.chars().collect();
52        let mut max = 0;
53        let mut result: String = String::from("");
54        for i in 1..chs.len() - 1 {
55            if chs[i - 1] == chs[i] && chs[i] == chs[i + 1] {
56                let t = num[i - 1..i + 2].to_string().parse::<i32>().unwrap();
57                if t >= max {
58                    max = t;
59                    result = num[i - 1..i + 2].into();
60                }
61            }
62        }
63        result
64    }
65}
66
67// submission codes end
68
69#[cfg(test)]
70mod tests {
71    use super::*;
72
73    #[test]
74    fn test_2264_1() {
75        assert_eq!(Solution::largest_good_integer(String::from("222")), "222");
76        assert_eq!(Solution::largest_good_integer(String::from("42352338")), "");
77        assert_eq!(Solution::largest_good_integer(String::from("23<u>000</u>19")), "000");
78        assert_eq!(Solution::largest_good_integer(String::from("6<u>777</u>133339")), "777");
79        assert_eq!(Solution::largest_good_integer(String::from("666<u>777</u>133339")), "777");
80    }
81}
82