problem: new problem solution - 2264 . Largest 3-Same-Digit Number in…

… String

README.md

@@ -118,6 +118,7 @@ My approach to solving LeetCode problems typically involves the following steps:
 | 1662 | [Check If Two String Arrays are Equivalent](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent/)                             | Algorithms | [TypeScript](./problems/algorithms/checkIfTwoStringArraysAreEquivalent/CheckIfTwoStringArraysAreEquivalent.ts)                           | Easy       |
 | 1160 | [Find Words That Can Be Formed by Characters](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/)                         | Algorithms | [TypeScript](./problems/algorithms/findWordsThatCanBeFormedByCharacters/FindWordsThatCanBeFormedByCharacters.ts)                         | Easy       |
 | 1266 | [Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points/)                                               | Algorithms | [TypeScript](./problems/algorithms/minimumTimeVisitingAllPoints/MinimumTimeVisitingAllPoints.ts)                                         | Easy       |
+| 2264 | [Largest 3-Same-Digit Number in String](https://leetcode.com/problems/largest-3-same-digit-number-in-string/)                                     | Algorithms | [TypeScript](./problems/algorithms/largest3SameDigitNumberInString/Largest3SameDigitNumberInString.ts)                                   | Easy       |
 | ...  | ...                                                                                                                                               | ...        | ...                                                                                                                                      | ...        |
 
 In this table:

problems/algorithms/largest3SameDigitNumberInString/Largest3SameDigitNumberInString.test.ts

@@ -0,0 +1,32 @@
+// Source : https://leetcode.com/problems/largest-3-same-digit-number-in-string/
+// Author : Francisco Tomas
+// Date   : 2023-12-04
+
+import { largestGoodInteger } from "./Largest3SameDigitNumberInString";
+
+describe("largest 3-same-digit number in string", () => {
+  test("example 1", () => {
+    const result: string = largestGoodInteger("6777133339");
+    expect(result).toBe("777");
+  });
+
+  test("example 2", () => {
+    const result: string = largestGoodInteger("2300019");
+    expect(result).toBe("000");
+  });
+
+  test("example 3", () => {
+    const result: string = largestGoodInteger("42352338");
+    expect(result).toBe("");
+  });
+
+  test("complext example - example 4", () => {
+    const result: string = largestGoodInteger("3200014888");
+    expect(result).toBe("888");
+  });
+
+  test("another complex example - example 5", () => {
+    const result: string = largestGoodInteger("1134324999");
+    expect(result).toBe("999");
+  });
+});

problems/algorithms/largest3SameDigitNumberInString/Largest3SameDigitNumberInString.ts

@@ -0,0 +1,116 @@
+// Source : https://leetcode.com/problems/largest-3-same-digit-number-in-string/
+// Author : Francisco Tomas
+// Date   : 2023-12-04
+
+/*****************************************************************************************************
+ *
+ * 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 = "6777133339"
+ * Output: "777"
+ * Explanation: There are two distinct good integers: "777" and "333".
+ * "777" is the largest, so we return "777".
+ *
+ * Example 2:
+ *
+ * Input: num = "2300019"
+ * 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.
+ ******************************************************************************************************/
+
+/**
+ * string -> string
+ * return the maximum good integer in the given string, num, 
+ * as a string or an empty string, "", if no such integer exists
+ * NOTE: 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.
+
+ * Stub:
+ function largestGoodInteger(num: string): string {return ""}
+
+ * Tests:
+ * I: num = "6777133339" -> O: "777"
+ * I: num = "2300019" -> O: "000"
+ * I: num = "42352338" -> O: ""
+ * I: num = "3200014888" -> O: "888"
+ * I: num = "1134324999" -> O: "999"
+
+ * Template:
+ function largestGoodInteger(num: string): string {
+     return (... num)
+ }
+ */
+
+/**
+ * Time Complexity: O(n), where n is the length of num
+ * Space Complexity: O(1)
+
+ * Runtime: 53ms (95.45%)
+ * Memory: 44.51MB (63.64%)
+ */
+export function largestGoodIntegerV1(num: string): string {
+  let ans: string = "";
+  let j: number = 0;
+
+  for (let i: number = 1; i < num.length; i++) {
+    if (num[j] === num[i]) {
+      if (i - j === 2) {
+        const goodInt: string = num.slice(j, i + 1);
+        if (ans === "" || +ans < +goodInt) {
+          ans = goodInt;
+        }
+      }
+    } else {
+      j += i - j;
+    }
+  }
+
+  return ans;
+}
+
+/**
+ * Time Complexity: O(n), where n is the length of num
+ * Space Complexity: O(1)
+
+ * Runtime: 49ms (95.45%)
+ * Memory: 43.72MB (100.00%)
+ */
+export function largestGoodInteger(num: string): string {
+  let maxGoodInt: string = "\0";
+
+  for (let i: number = 2; i < num.length; i++) {
+    if (num[i] === num[i - 1] && num[i] === num[i - 2]) {
+      maxGoodInt = String.fromCharCode(
+        Math.max(maxGoodInt.charCodeAt(0), num.charCodeAt(i)),
+      );
+    }
+  }
+
+  return maxGoodInt === "\0" ? "" : maxGoodInt.repeat(3);
+}