1796. Second Largest Digit in a String: AC

Author: tan-wei

src/solution/mod.rs

@@ -1352,3 +1352,4 @@ mod s1790_check_if_one_string_swap_can_make_strings_equal;
 mod s1791_find_center_of_star_graph;
 mod s1792_maximum_average_pass_ratio;
 mod s1793_maximum_score_of_a_good_subarray;
+mod s1796_second_largest_digit_in_a_string;

src/solution/s1796_second_largest_digit_in_a_string.rs

@@ -0,0 +1,73 @@
+/**
+ * [1796] Second Largest Digit in a String
+ *
+ * Given an alphanumeric string s, return the second largest numerical digit that appears in s, or -1 if it does not exist.
+ * An alphanumeric string is a string consisting of lowercase English letters and digits.
+ *  
+ * Example 1:
+ *
+ * Input: s = "dfa12321afd"
+ * Output: 2
+ * Explanation: The digits that appear in s are [1, 2, 3]. The second largest digit is 2.
+ *
+ * Example 2:
+ *
+ * Input: s = "abc1111"
+ * Output: -1
+ * Explanation: The digits that appear in s are [1]. There is no second largest digit.
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= s.length <= 500
+ * 	s consists of only lowercase English letters and digits.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/second-largest-digit-in-a-string/
+// discuss: https://leetcode.com/problems/second-largest-digit-in-a-string/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn second_highest(s: String) -> i32 {
+        s.bytes()
+            .filter_map(|b| b.is_ascii_digit().then_some((b - b'0') as i32))
+            .fold((-1, -1), |(p, u), d| {
+                if d > u {
+                    (u, d)
+                } else if d > p && d < u {
+                    (d, u)
+                } else {
+                    (p, u)
+                }
+            })
+            .0
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1796_example_1() {
+        let s = "dfa12321afd".to_string();
+
+        let result = 2;
+
+        assert_eq!(Solution::second_highest(s), result);
+    }
+
+    #[test]
+    fn test_1796_example_2() {
+        let s = "abc1111".to_string();
+
+        let result = -1;
+
+        assert_eq!(Solution::second_highest(s), result);
+    }
+}