2264. Largest 3-Same-Digit Number in String: AC

Author: tan-wei

src/solution/mod.rs

@@ -1713,3 +1713,4 @@ mod s2259_remove_digit_from_number_to_maximize_result;
 mod s2260_minimum_consecutive_cards_to_pick_up;
 mod s2261_k_divisible_elements_subarrays;
 mod s2262_total_appeal_of_a_string;
+mod s2264_largest_3_same_digit_number_in_string;

src/solution/s2264_largest_3_same_digit_number_in_string.rs

@@ -0,0 +1,93 @@
+/**
+ * [2264] Largest 3-Same-Digit Number in String
+ *
+ * You are given a string num representing a large integer. An integer is good if it meets the following conditions:
+ *
+ * 	It is a substring of num with length 3.
+ * 	It consists of only one unique digit.
+ *
+ * Return the maximum good integer as a string or an empty string "" if no such integer exists.
+ * Note:
+ *
+ * 	A substring is a contiguous sequence of characters within a string.
+ * 	There may be leading zeroes in num or a good integer.
+ *
+ *  
+ * Example 1:
+ *
+ * Input: num = "6<u>777</u>133339"
+ * Output: "777"
+ * Explanation: There are two distinct good integers: "777" and "333".
+ * "777" is the largest, so we return "777".
+ *
+ * Example 2:
+ *
+ * Input: num = "23<u>000</u>19"
+ * Output: "000"
+ * Explanation: "000" is the only good integer.
+ *
+ * Example 3:
+ *
+ * Input: num = "42352338"
+ * Output: ""
+ * Explanation: No substring of length 3 consists of only one unique digit. Therefore, there are no good integers.
+ *
+ *  
+ * Constraints:
+ *
+ * 	3 <= num.length <= 1000
+ * 	num only consists of digits.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/largest-3-same-digit-number-in-string/
+// discuss: https://leetcode.com/problems/largest-3-same-digit-number-in-string/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn largest_good_integer(num: String) -> String {
+        num.as_bytes()
+            .windows(3)
+            .filter(|bytes| bytes.iter().all(|&b| b == bytes[0])) //[[55,55,55]], [57,57,57]]
+            .map(|b| b[0])
+            .max()
+            .map(|b| (b as char).to_string().repeat(3))
+            .unwrap_or_default() //"999"
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2264_example_1() {
+        let num = "6777133339".to_string();
+
+        let result = "777".to_string();
+
+        assert_eq!(Solution::largest_good_integer(num), result);
+    }
+
+    #[test]
+    fn test_2264_example_2() {
+        let num = "2300019".to_string();
+
+        let result = "000".to_string();
+
+        assert_eq!(Solution::largest_good_integer(num), result);
+    }
+
+    #[test]
+    fn test_2264_example_3() {
+        let num = "42352338".to_string();
+
+        let result = "".to_string();
+
+        assert_eq!(Solution::largest_good_integer(num), result);
+    }
+}