Some solved problems from LeetCode on Ruby.
Profile on LeetCode: fartem.
| Name | Link to LeetCode | Link to solution |
|---|---|---|
| 1. Two Sum | Link | Link |
| 9. Palindrome Number | Link | Link |
| 13. Roman to Integer | Link | Link |
| 14. Longest Common Prefix | Link | Link |
| 20. Valid Parentheses | Link | Link |
| 21. Merge Two Sorted Lists | Link | Link |
| 26. Remove Duplicates from Sorted Array | Link | Link |
| 27. Remove Element | Link | Link |
| 28. Find the Index of the First Occurrence in a String | Link | Link |
| 35. Search Insert Position | Link | Link |
| 58. Length of Last Word | Link | Link |
| 66. Plus One | Link | Link |
| 67. Add Binary | Link | Link |
| 69. Sqrt(x) | Link | Link |
| 70. Climbing Stairs | Link | Link |
| 83. Remove Duplicates from Sorted List | Link | Link |
| 88. Merge Sorted Array | Link | Link |
| 94. Binary Tree Inorder Traversal | Link | Link |
| 100. Same Tree | Link | Link |
| 101. Symmetric Tree | Link | Link |
| 104. Maximum Depth of Binary Tree | Link | Link |
| 108. Convert Sorted Array to Binary Search Tree | Link | Link |
| 110. Balanced Binary Tree | Link | Link |
| 111. Minimum Depth of Binary Tree | Link | Link |
| 112. Path Sum | Link | Link |
| 118. Pascal's Triangle | Link | Link |
| 119. Pascal's Triangle II | Link | Link |
| 121. Best Time to Buy and Sell Stock | Link | Link |
| 125. Valid Palindrome | Link | Link |
| 136. Single Number | Link | Link |
| 141. Linked List Cycle | Link | Link |
| 144. Binary Tree Preorder Traversal | Link | Link |
| 145. Binary Tree Postorder Traversal | Link | Link |
| 160. Intersection of Two Linked Lists | Link | Link |
| 168. Excel Sheet Column Title | Link | Link |
| 169. Majority Element | Link | Link |
| 171. Excel Sheet Column Number | Link | Link |
| 190. Reverse Bits | Link | Link |
| 191. Number of 1 Bits | Link | Link |
| 202. Happy Number | Link | Link |
| 203. Remove Linked List Elements | Link | Link |
| 205. Isomorphic Strings | Link | Link |
| 206. Reverse Linked List | Link | Link |
| 217. Contains Duplicate | Link | Link |
| 219. Contains Duplicate II | Link | Link |
| 225. Implement Stack using Queues | Link | Link |
| 226. Invert Binary Tree | Link | Link |
| 228. Summary Ranges | Link | Link |
| 231. Power of Two | Link | Link |
| 232. Implement Queue using Stacks | Link | Link |
| 234. Palindrome Linked List | Link | Link |
| 242. Valid Anagram | Link | Link |
| 257. Binary Tree Paths | Link | Link |
| 258. Add Digits | Link | Link |
| 263. Ugly Number | Link | Link |
| 268. Missing Number | Link | Link |
| 278. First Bad Version | Link | Link |
| 283. Move Zeroes | Link | Link |
| 290. Word Pattern | Link | Link |
| 292. Nim Game | Link | Link |
| 303. Range Sum Query - Immutable | Link | Link |
| 326. Power of Three | Link | Link |
| 338. Counting Bits | Link | Link |
| 342. Power of Four | Link | Link |
| 344. Reverse String | Link | Link |
| 345. Reverse Vowels of a String | Link | Link |
| 349. Intersection of Two Arrays | Link | Link |
| 350. Intersection of Two Arrays II | Link | Link |
| 367. Valid Perfect Square | Link | Link |
| 374. Guess Number Higher or Lower | Link | Link |
| 383. Ransom Note | Link | Link |
| 387. First Unique Character in a String | Link | Link |
| 389. Find the Difference | Link | Link |
| 392. Is Subsequence | Link | Link |
| 404. Sum of Left Leaves | Link | Link |
| 405. Convert a Number to Hexadecimal | Link | Link |
| 409. Longest Palindrome | Link | Link |
| 412. Fizz Buzz | Link | Link |
| 414. Third Maximum Number | Link | Link |
| 415. Add Strings | Link | Link |
| 434. Number of Segments in a String | Link | Link |
| 441. Arranging Coins | Link | Link |
| 448. Find All Numbers Disappeared in an Array | Link | Link |
| 455. Assign Cookies | Link | Link |
| 459. Repeated Substring Pattern | Link | Link |
| 461. Hamming Distance | Link | Link |
| 463. Island Perimeter | Link | Link |
| 476. Number Complement | Link | Link |
| 482. License Key Formatting | Link | Link |
| 485. Max Consecutive Ones | Link | Link |
| 492. Construct the Rectangle | Link | Link |
| 496. Next Greater Element I | Link | Link |
| 500. Keyboard Row | Link | Link |
| 501. Find Mode in Binary Search Tree | Link | Link |
| 504. Base 7 | Link | Link |
| 506. Relative Ranks | Link | Link |
| 507. Perfect Number | Link | Link |
| 509. Fibonacci Number | Link | Link |
| 520. Detect Capital | Link | Link |
| 521. Longest Uncommon Subsequence I | Link | Link |
| 530. Minimum Absolute Difference in BST | Link | Link |
| 543. Diameter of Binary Tree | Link | Link |
| 551. Student Attendance Record I | Link | Link |
| 557. Reverse Words in a String III | Link | Link |
| 559. Maximum Depth of N-ary Tree | Link | Link |
| 561. Array Partition | Link | Link |
| 563. Binary Tree Tilt | Link | Link |
| 566. Reshape the Matrix | Link | Link |
| 572. Subtree of Another Tree | Link | Link |
| 589. N-ary Tree Preorder Traversal | Link | Link |
| 590. N-ary Tree Postorder Traversal | Link | Link |
| 594. Longest Harmonious Subsequence | Link | Link |
| 599. Minimum Index Sum of Two Lists | Link | Link |
| 606. Construct String from Binary Tree | Link | Link |
| 617. Merge Two Binary Trees | Link | Link |
| 628. Maximum Product of Three Numbers | Link | Link |
| 637. Average of Levels in Binary Tree | Link | Link |
| 643. Maximum Average Subarray I | Link | Link |
| 645. Set Mismatch | Link | Link |
| 653. Two Sum IV - Input is a BST | Link | Link |
| 657. Robot Return to Origin | Link | Link |
| 671. Second Minimum Node In a Binary Tree | Link | Link |
| 674. Longest Continuous Increasing Subsequence | Link | Link |
| 680. Valid Palindrome II | Link | Link |
| 682. Baseball Game | Link | Link |
| 693. Binary Number with Alternating Bits | Link | Link |
| 700. Search in a Binary Search Tree | Link | Link |
| 703. Kth Largest Element in a Stream | Link | Link |
| 704. Binary Search | Link | Link |
| 705. Design HashSet | Link | Link |
| 706. Design HashMap | Link | Link |
| 709. To Lower Case | Link | Link |
| 717. 1-bit and 2-bit Characters | Link | Link |
| 724. Find Pivot Index | Link | Link |
| 728. Self Dividing Numbers | Link | Link |
| 733. Flood Fill | Link | Link |
| 744. Find Smallest Letter Greater Than Target | Link | Link |
| 746. Min Cost Climbing Stairs | Link | Link |
| 747. Largest Number At Least Twice of Others | Link | Link |
| 762. Prime Number of Set Bits in Binary Representation | Link | Link |
| 766. Toeplitz Matrix | Link | Link |
| 771. Jewels and Stones | Link | Link |
| 783. Minimum Distance Between BST Nodes | Link | Link |
| 796. Rotate String | Link | Link |
| 804. Unique Morse Code Words | Link | Link |
| 806. Number of Lines To Write String | Link | Link |
| 812. Largest Triangle Area | Link | Link |
| 819. Most Common Word | Link | Link |
| 821. Shortest Distance to a Character | Link | Link |
| 830. Positions of Large Groups | Link | Link |
| 832. Flipping an Image | Link | Link |
| 844. Backspace String Compare | Link | Link |
| 859. Buddy Strings | Link | Link |
| 860. Lemonade Change | Link | Link |
| 867. Transpose Matrix | Link | Link |
| 868. Binary Gap | Link | Link |
| 872. Leaf-Similar Trees | Link | Link |
| 876. Middle of the Linked List | Link | Link |
| 884. Uncommon Words from Two Sentences | Link | Link |
| 896. Monotonic Array | Link | Link |
| 897. Increasing Order Search Tree | Link | Link |
| 905. Sort Array By Parity | Link | Link |
| 908. Smallest Range I | Link | Link |
| 917. Reverse Only Letters | Link | Link |
| 922. Sort Array By Parity II | Link | Link |
| 925. Long Pressed Name | Link | Link |
| 929. Unique Email Addresses | Link | Link |
| 933. Number of Recent Calls | Link | Link |
| 938. Range Sum of BST | Link | Link |
| 941. Valid Mountain Array | Link | Link |
| 942. DI String Match | Link | Link |
| 944. Delete Columns to Make Sorted | Link | Link |
| 953. Verifying an Alien Dictionary | Link | Link |
| 961. N-Repeated Element in Size 2N Array | Link | Link |
| 965. Univalued Binary Tree | Link | Link |
| 976. Largest Perimeter Triangle | Link | Link |
| 977. Squares of a Sorted Array | Link | Link |
| 989. Add to Array-Form of Integer | Link | Link |
| 993. Cousins in Binary Tree | Link | Link |
| 997. Find the Town Judge | Link | Link |
| 1002. Find Common Characters | Link | Link |
| 1005. Maximize Sum Of Array After K Negations | Link | Link |
| 1009. Complement of Base 10 Integer | Link | Link |
| 1018. Binary Prefix Divisible By 5 | Link | Link |
| 1021. Remove Outermost Parentheses | Link | Link |
| 1022. Sum of Root To Leaf Binary Numbers | Link | Link |
| 1025. Divisor Game | Link | Link |
| 1046. Last Stone Weight | Link | Link |
| 1047. Remove All Adjacent Duplicates In String | Link | Link |
| 1051. Height Checker | Link | Link |
| 1071. Greatest Common Divisor of Strings | Link | Link |
| 1078. Occurrences After Bigram | Link | Link |
| 1089. Duplicate Zeros | Link | Link |
| 1103. Distribute Candies to People | Link | Link |
| 1108. Defanging an IP Address | Link | Link |
| 1137. N-th Tribonacci Number | Link | Link |
| 1154. Day of the Year | Link | Link |
| 1160. Find Words That Can Be Formed by Characters | Link | Link |
| 1184. Distance Between Bus Stops | Link | Link |
| 1185. Day of the Week | Link | Link |
| 1189. Maximum Number of Balloons | Link | Link |
| 1200. Minimum Absolute Difference | Link | Link |
| 1207. Unique Number of Occurrences | Link | Link |
| 1217. Minimum Cost to Move Chips to The Same Position | Link | Link |
| 1221. Split a String in Balanced Strings | Link | Link |
| 1232. Check If It Is a Straight Line | Link | Link |
| 1252. Cells with Odd Values in a Matrix | Link | Link |
| 1266. Minimum Time Visiting All Points | Link | Link |
| 1275. Find Winner on a Tic Tac Toe Game | Link | Link |
| 1281. Subtract the Product and Sum of Digits of an Integer | Link | Link |
| 1287. Element Appearing More Than 25% In Sorted Array | Link | Link |
| 1290. Convert Binary Number in a Linked List to Integer | Link | Link |
| 1295. Find Numbers with Even Number of Digits | Link | Link |
| 1299. Replace Elements with Greatest Element on Right Side | Link | Link |
| 1304. Find N Unique Integers Sum up to Zero | Link | Link |
| 1309. Decrypt String from Alphabet to Integer Mapping | Link | Link |
| 1313. Decompress Run-Length Encoded List | Link | Link |
| 1317. Convert Integer to the Sum of Two No-Zero Integers | Link | Link |
| 1323. Maximum 69 Number | Link | Link |
| 1332. Remove Palindromic Subsequences | Link | Link |
| 1337. The K Weakest Rows in a Matrix | Link | Link |
| 1342. Number of Steps to Reduce a Number to Zero | Link | Link |
| 1346. Check If N and Its Double Exist | Link | Link |
| 1351. Count Negative Numbers in a Sorted Matrix | Link | Link |
| 1356. Sort Integers by The Number of 1 Bits | Link | Link |
| 1360. Number of Days Between Two Dates | Link | Link |
| 1365. How Many Numbers Are Smaller Than the Current Number | Link | Link |
| 1370. Increasing Decreasing String | Link | Link |
| 1374. Generate a String With Characters That Have Odd Counts | Link | Link |
| 1385. Find the Distance Value Between Two Arrays | Link | Link |
| 1389. Create Target Array in the Given Order | Link | Link |
| 1399. Count Largest Group | Link | Link |
| 1403. Minimum Subsequence in Non-Increasing Order | Link | Link |
| 1408. String Matching in an Array | Link | Link |
| 1413. Minimum Value to Get Positive Step by Step Sum | Link | Link |
| 1417. Reformat The String | Link | Link |
| 1422. Maximum Score After Splitting a String | Link | Link |
| 1431. Kids With the Greatest Number of Candies | Link | Link |
| 1436. Destination City | Link | Link |
| 1437. Check If All 1's Are at Least Length K Places Away | Link | Link |
| 1446. Consecutive Characters | Link | Link |
| 1450. Number of Students Doing Homework at a Given Time | Link | Link |
| 1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence | Link | Link |
| 1460. Make Two Arrays Equal by Reversing Subarrays | Link | Link |
| 1464. Maximum Product of Two Elements in an Array | Link | Link |
| 1470. Shuffle the Array | Link | Link |
| 1475. Final Prices With a Special Discount in a Shop | Link | Link |
| 1480. Running Sum of 1d Array | Link | Link |
| 1486. XOR Operation in an Array | Link | Link |
| 1491. Average Salary Excluding the Minimum and Maximum Salary | Link | Link |
| 1496. Path Crossing | Link | Link |
| 1502. Can Make Arithmetic Progression From Sequence | Link | Link |
| 1507. Reformat Date | Link | Link |
| 1512. Number of Good Pairs | Link | Link |
| 1518. Water Bottle | Link | Link |
| 1523. Count Odd Numbers in an Interval Range | Link | Link |
| 1528. Shuffle String | Link | Link |
| 1534. Count Good Triplets | Link | Link |
| 1539. Kth Missing Positive Number | Link | Link |
| 1544. Make The String Great | Link | Link |
| 1550. Three Consecutive Odds | Link | Link |
| 1556. Thousand Separator | Link | Link |
| 1566. Detect Pattern of Length M Repeated K or More Times | Link | Link |
| 1572. Matrix Diagonal Sum | Link | Link |
| 1576. Replace All ?'s to Avoid Consecutive Repeating Characters | Link | Link |
| 1582. Special Positions in a Binary Matrix | Link | Link |
| 1588. Sum of All Odd Length Subarrays | Link | Link |
| 1592. Rearrange Spaces Between Words | Link | Link |
| 1598. Crawler Log Folder | Link | Link |
| 1603. Design Parking System | Link | Link |
| 1608. Special Array With X Elements Greater Than or Equal X | Link | Link |
| 1614. Maximum Nesting Depth of the Parentheses | Link | Link |
| 1619. Mean of Array After Removing Some Elements | Link | Link |
| 1624. Largest Substring Between Two Equal Characters | Link | Link |
| 1629. Slowest Key | Link | Link |
| 1636. Sort Array by Increasing Frequency | Link | Link |
| 1646. Get Maximum in Generated Array | Link | Link |
| 1652. Defuse the Bomb | Link | Link |
| 1662. Check If Two String Arrays are Equivalent | Link | Link |
| 1668. Maximum Repeating Substring | Link | Link |
| 1672. Richest Customer Wealth | Link | Link |
| 1678. Goal Parser Interpretation | Link | Link |
| 1684. Count the Number of Consistent Strings | Link | Link |
| 1688. Count of Matches in Tournament | Link | Link |
| 1694. Reformat Phone Number | Link | Link |
| 1700. Number of Students Unable to Eat Lunch | Link | Link |
| 1704. Determine if String Halves Are Alike | Link | Link |
| 1710. Maximum Units on a Truck | Link | Link |
| 1716. Calculate Money in Leetcode Bank | Link | Link |
| 1720. Decode XORed Array | Link | Link |
| 1725. Number Of Rectangles That Can Form The Largest Square | Link | Link |
| 1732. Find the Highest Altitude | Link | Link |
| 1736. Latest Time by Replacing Hidden Digits | Link | Link |
| 1748. Sum of Unique Elements | Link | Link |
| 1752. Check if Array Is Sorted and Rotated | Link | Link |
| 1768. Merge Strings Alternately | Link | Link |
| 1773. Count Items Matching a Rule | Link | Link |
| 1779. Find Nearest Point That Has the Same X or Y Coordinate | Link | Link |
| 1784. Check if Binary String Has at Most One Segment of Ones | Link | Link |
| 1790. Check if One String Swap Can Make Strings Equal | Link | Link |
| 1791. Find Center of Star Graph | Link | Link |
| 1796. Second Largest Digit in a String | Link | Link |
| 1800. Maximum Ascending Subarray Sum | Link | Link |
| 1805. Number of Different Integers in a String | Link | Link |
| 1812. Determine Color of a Chessboard Square | Link | Link |
| 1816. Truncate Sentence | Link | Link |
| 1822. Sign of the Product of an Array | Link | Link |
| 1827. Minimum Operations to Make the Array Increasing | Link | Link |
| 1832. Check if the Sentence Is Pangram | Link | Link |
| 1837. Sum of Digits in Base K | Link | Link |
| 1844. Replace All Digits with Characters | Link | Link |
| 1848. Minimum Distance to the Target Element | Link | Link |
| 1859. Sorting the Sentence | Link | Link |
| 1863. Sum of All Subset XOR Totals | Link | Link |
| 1869. Longer Contiguous Segments of Ones than Zeros | Link | Link |
| 1876. Substrings of Size Three with Distinct Characters | Link | Link |
| 1880. Check if Word Equals Summation of Two Words | Link | Link |
| 1886. Determine Whether Matrix Can Be Obtained By Rotation | Link | Link |
| 1893. Check if All the Integers in a Range Are Covered | Link | Link |
| 1897. Redistribute Characters to Make All Strings Equal | Link | Link |
| 1903. Largest Odd Number in String | Link | Link |
| 1909. Remove One Element to Make the Array Strictly Increasing | Link | Link |
| 1913. Maximum Product Difference Between Two Pairs | Link | Link |
| 1920. Build Array from Permutation | Link | Link |
| 1925. Count Square Sum Triples | Link | Link |
| 1929. Concatenation of Array | Link | Link |
| 1935. Maximum Number of Words You Can Type | Link | Link |
| 1941. Check if All Characters Have Equal Number of Occurrences | Link | Link |
| 1952. Three Divisors | Link | Link |
| 1957. Delete Characters to Make Fancy String | Link | Link |
| 1961. Check If String Is a Prefix of Array | Link | Link |
| 1967. Number of Strings That Appear as Substrings in Word | Link | Link |
| 1971. Find if Path Exists in Graph | Link | Link |
| 1974. Minimum Time to Type Word Using Special Typewriter | Link | Link |
| 1979. Find Greatest Common Divisor of Array | Link | Link |
| 1984. Minimum Difference Between Highest and Lowest of K Scores | Link | Link |
| 1991. Find the Middle Index in Array | Link | Link |
| 1995. Count Special Quadruplets | Link | Link |
| 2000. Reverse Prefix of Word | Link | Link |
| 2006. Count Number of Pairs With Absolute Difference K | Link | Link |
| 2011. Final Value of Variable After Performing Operations | Link | Link |
| 2016. Maximum Difference Between Increasing Elements | Link | Link |
| 2022. Convert 1D Array Into 2D Array | Link | Link |
| 2027. Minimum Moves to Convert String | Link | Link |
| 2032. Two Out of Three | Link | Link |
| 2037. Minimum Number of Moves to Seat Everyone | Link | Link |
| 2042. Check if Numbers Are Ascending in a Sentence | Link | Link |
| 2047. Number of Valid Words in a Sentence | Link | Link |
| 2053. Kth Distinct String in an Array | Link | Link |
| 2057. Smallest Index With Equal Value | Link | Link |
| 2062. Count Vowel Substrings of a String | Link | Link |
| 2068. Check Whether Two Strings are Almost Equivalent | Link | Link |
| 2073. Time Needed to Buy Tickets | Link | Link |
| 2078. Two Furthest Houses With Different Colors | Link | Link |
| 2085. Count Common Words With One Occurrence | Link | Link |
| 2089. Find Target Indices After Sorting Array | Link | Link |
| 2094. Finding 3-Digit Even Numbers | Link | Link |
| 2099. Find Subsequence of Length K With the Largest Sum | Link | Link |
| 2103. Rings and Rods | Link | Link |
| 2108. Find First Palindromic String in the Array | Link | Link |
| 2114. Maximum Number of Words Found in Sentences | Link | Link |
| 2119. A Number After a Double Reversal | Link | Link |
| 2124. Check if All A's Appears Before All B's | Link | Link |
| 2129. Capitalize the Title | Link | Link |
| 2133. Check if Every Row and Column Contains All Numbers | Link | Link |
| 2138. Divide a String Into Groups of Size k | Link | Link |
| 2148. Count Elements With Strictly Smaller and Greater Elements | Link | Link |
| 2154. Keep Multiplying Found Values by Two | Link | Link |
| 2160. Minimum Sum of Four Digit Number After Splitting Digits | Link | Link |
| 2164. Sort Even and Odd Indices Independently | Link | Link |
| 2169. Count Operations to Obtain Zero | Link | Link |
| 2176. Count Equal and Divisible Pairs in an Array | Link | Link |
| 2180. Count Integers With Even Digit Sum | Link | Link |
| 2185. Counting Words With a Given Prefix | Link | Link |
| 2190. Most Frequent Number Following Key In an Array | Link | Link |
| 2194. Cells in a Range on an Excel Sheet | Link | Link |
| 2206. Divide Array Into Equal Pairs | Link | Link |
| 2210. Count Hills and Valleys in an Array | Link | Link |
| 2215. Find the Difference of Two Arrays | Link | Link |
| 2220. Minimum Bit Flips to Convert Number | Link | Link |
| 2231. Largest Number After Digit Swaps by Parity | Link | Link |
| 2235. Add Two Integers | Link | Link |
| 2236. Root Equals Sum of Children | Link | Link |
| 2239. Find Closest Number to Zero | Link | Link |
| 2243. Calculate Digit Sum of a String | Link | Link |
| 2248. Intersection of Multiple Arrays | Link | Link |
| 2255. Count Prefixes of a Given String | Link | Link |
| 2259. Remove Digit From Number to Maximize Result | Link | Link |
| 2264. Largest 3-Same-Digit Number in String | Link | Link |