LeetCode Solutions

Algorithms

• Math
• Bit Manipulation
• Array
• String
• Matrix
• Hash Table
• Binary Search
• Sorting
• Two Pointers
• Dynamic Programming

My Most Voted Solutions

#	Title	Explanation	Existence	Complexity	Difficulty	Tags
8	String to Integer (atoi)	Detailed Explanation	On 1st page of Most Voted Category	Time - O(n) Space - O(1)	Medium	String
50	Pow(x, n)	Detailed Explanation	On 1st page of Most Voted Category	Time - O(log2(n)) Space - O(1)	Medium	Math, Recursion
190	Reverse Bits	Detailed Explanation	On 1st page of Most Voted Category	Time - O(1) Space - O(1)	Easy	Divide and Conquer, Bit Manipuation
989	Add to Array-Form of Integer	Detailed Explanation	On 1st page of Most Voted Category	Time - O(max(n, log10(k))) Space - O(max(n, log10(k)))	Easy	Array, Math
1470	Shuffle the Array	Detailed Explanation	On 1st page of Most Voted Category	Time - O(n) Space - O(1)	Easy	Array
2129	Capitalize the Title	Explained Solution	On 1st page of Most Voted Category	Time - O(n) Space - O(1)	Easy	String

Explained Solutions

#	Title	Explanation	Complexity	Difficulty	Tags
8	String to Integer (atoi)	Detailed Explanation	Time - O(n) Space - O(1)	Medium	String
9	Palindrome Number	Explained Solution	Time - O(log10(n)) Space - O(1)	Easy	Math
33	Search in Rotated Sorted Array	C++ Explanation JAVA Explanation	Time - O(log2(n)) Space - O(1)	Medium	Array, Binary Search
50	Pow(x, n)	Detailed Explanation	Time - O(log2(n)) Space - O(1)	Medium	Math, Recursion
189	Rotate Array	C++ Explanation JAVA Explanation	Time - O(n) Space - O(1)	Medium	Math, Array, Two Pointers
190	Reverse Bits	Detailed Explanation	Time - O(1) Space - O(1)	Easy	Divide and Conquer, Bit Manipuation
191	Number of 1 Bits	Detailed Explanation	Time - O(1) Space - O(1)	Easy	Bit Manipulation
1431	Kids With the Greatest Number of Candies	Commented Solution	Time - O(n) Space - O(n)	Easy	Array
1470	Shuffle The Array	Detailed Explanation	Time - O(n) Space - O(1)	Easy	Array
2129	Capitalize the Title	Explained Solution	Time - O(n) Space - O(1)	Easy	String
2130	Rings and Rods	Detailed Explanation	Time - O(n) Space - O(1)	Easy	HashTable

Math

#	Title	Solution	Complexity	Difficulty	Tags
7	Reverse Integer	C++ JAVA	Time - O(log10(n)) Space - O(1)	Medium
9	Palindrome Number	C++ JAVA	Time - O(log10(n)) Space - O(1)	Easy
50	Pow(x, n)	JAVA	Time - O(log2(n)) Space - O(1)	Medium	Recursion
172	Factorial Trailing Zeroes	C++ JAVA	Time - O(log5(n)) Space - O(1)	Medium
231	Power Of Two	C++ JAVA	Time - O(1) Space - O(1)	Easy	Bit Manipuation, Recursion
258	Add Digits	C++ JAVA	Time - O(1) Space - O(1)	Easy	Simulation, Number Theory
263	Ugly Number	C++ JAVA	Time - O(log2(n)) Space - O(1)	Easy
1137	N-th Tribonacci Number	C++ JAVA	Time - O(n) Space - O(1)	Easy	Dynamic Programming, Memoization
1281	Subtract the Product and Sum of Digits of an Integer	C++ JAVA	Time - O(n) Space - O(1)	Easy
1342	Number of Steps to Reduce a Number to Zero	C++ JAVA	Time - O(log2(n)) Space - O(1)	Easy	Bit Manipuation
1551	Minimum Operations to Make Array Equal	C++ JAVA	Time - O(1) Space - O(1)	Medium
1688	Count of Matches in Tournament	C++ JAVA	Time - O(1) Space - O(1)	Easy	Simulation

Bit Manipulation

#	Title	Solution	Complexity	Difficulty	Tags
191	Number of 1 Bits	C++ JAVA	Time - O(1) Space - O(1)	Easy
476	Number Complement	C++ JAVA	Time - O(log2(n)) Space - O(1)	Easy
1009	Complement of Base 10 Integer	C++ JAVA	Time - O(log2(n)) Space - O(1)	Easy

Array

#	Title	Solution	Complexity	Difficulty
1	Two Sum	JAVA	Time - O(n) Space - O(n)	Easy
53	Maximum Subarray	C++ JAVA	Time - O(n) Space - O(1)	Easy
80	Remove Duplicates from Sorted Array II	C++ JAVA	Time - O(n) Space - O(1)	Medium
121	Best Time to Buy and Sell Stock	C++ JAVA	Time - O(n) Space - O(1)	Easy
122	Best Time to Buy and Sell Stock II	C++ JAVA	Time - O(n) Space - O(1)	Medium
136	Single Number	C++ JAVA	Time - O(n) Space - O(1)	Easy
162	Find Peak Element	C++ JAVA	Time - O(log2(n)) Space - O(1)	Medium
169	Majority Element	C++ JAVA	Time - O(n) Space - O(1)	Easy
189	Rotate Array	C++ JAVA, Explanation	Time - O(n) Space - O(1)	Medium
228	Summary Ranges	JAVA	Time - O(n) Space - O(1)	Easy
229	Majority Element II	C++ JAVA	Time - O(n) Space - O(1)	Medium
287	Find the Duplicate Number	JAVA	Time - O(n) Space - O(1)	Medium
413	Arithmetic Slices	C++ JAVA	Time - O(n) Space - O(1)	Medium
414	Third Maximum Number	JAVA	Time - O(n) Space - O(1)	Easy
500	Keyboard Row	JAVA	Time - O(N) Space - O(n)	Easy
525	Contiguous Array	C++ JAVA	Time - O(n) Space - O(n)	Medium
532	K-diff Pairs in an Array	C++ JAVA	Time - O(n) Space - O(n)	Medium
648	Replace Words	JAVA	Time - O(m * n) Space - O(n)	Medium
739	Daily Temperatures	JAVA	Time - O(n) Space - O(n)	Medium
746	Min Cost Climbing Stairs	C++ JAVA	Time - O(n) Space - O(1)	Easy
811	Subdomain Visit Count	JAVA	Time - O(n * m) Space - O(n)	Medium
881	Boats to Save People	JAVA	Time - O(n logn) Space - O(1)	Medium
848	Shifting Letters	C++ JAVA	Time - O(n) Space - O(1)	Medium
941	Valid Mountain Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1094	Car Pooling	C++ JAVA	Time - O(n) Space - O(n)	Medium
1207	Unique Number of Occurrences	JAVA	Time - O(n) Space - O(n)	Easy
1282	Group the People Given the Group Size They Belong To	JAVA	Time - O(n) Space - O(n)	Medium
1295	Find Numbers with Even Number of Digits	C++ JAVA	Time - O(n) Space - O(1)	Easy
1365	How Many Numbers Are Smaller Than the Current Number	C++ JAVA	Time - O(n + m) Space - O(m)	Easy
1431	Kids With the Greatest Number of Candies	C++ JAVA	Time - O(n) Space - O(n)	Easy
1441	Build an Array With Stack Operations	JAVA	Time - O(n) Space - O(n)	Easy
1464	Maximum Product of Two Elements in an Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1470	Shuffle The Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1480	Running Sum of 1d Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1512	Number of Good Pairs	C++ JAVA	Time - O(n) Space - O(n)	Easy
1550	Three Consecutive Odds	C++ JAVA	Time - O(n) Space - O(1)	Easy
1646	Get Maximum in Generated Array	C++ JAVA	Time - O(n) Space - O(n)	Easy
1662	Check If Two String Arrays are Equivalent	C++ JAVA	Time - O(n) Space - O(1)	Easy
1672	Richest Customer Wealth	C++ JAVA	Time - O(m * n) Space - O(1)	Easy
1720	Decode XORed Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1748	Sum of Unique Elements	C++ JAVA	Time - O(n) Space - O(m)	Easy
1909	Remove One Element to Make the Array Strictly Increasing	C++ JAVA	Time - O(n) Space - O(1)	Easy
1929	Concatenation of Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1979	Find Greatest Common Divisor of Array	C++ JAVA	Time - O(n) Space - O(1)	Easy
1980	Find Unique Binary String	C++ JAVA	Time - O(n) Space - O(1)	Medium
2006	Count Number of Pairs With Absolute Difference K	C++ JAVA	Time - O(n + m) Space - O(m)	Easy
2011	Final Value of Variable After Performing Operations	C++ JAVA	Time - O(n) Space - O(m)	Easy
2023	Number of Pairs of Strings With Concatenation Equal to Target	JAVA	Time - O(n * m) Space - O(n)	Easy
2078	Two Furthest Houses With Different Colors	C++ JAVA	Time - O(n) Space - O(1)	Easy
2079	Watering Plants	C++ JAVA	Time - O(n) Space - O(1)	Medium
2114	Maximum Number of Words Found in Sentences	C++ JAVA	Time - O(n * m) Space - O(1)	Easy
2125	Number of Laser Beams in a Bank	C++ JAVA	Time - O(n * m) Space - O(1)	Medium
2161	Partition Array According to Given Pivot	JAVA	Time - O(n) Space - O(1)	Medium

String

#	Title	Solution	Complexity	Difficulty
5	Longest Palindromic Substring	JAVA	Time - O(n2) Space - O(1)	Medium
49	Group Anagrams	JAVA	Time - O(n * m) Space - O(n)	Medium
67	Add Binary	JAVA	Time - O(max(n, m)) Space - O(max(n, m))	Easy
125	Valid Palindrome	C++ JAVA	Time - O(n) Space - O(1)	Easy
151	Reverse Words in a String	JAVA	Time - O(n * m) Space - O(n)	Medium
165	Compare Version Numbers	C++ JAVA	Time - O(max(n, m)) Space - O(1)	Medium
171	Excel Sheet Column Number	C++ JAVA	Time - O(n) Space - O(1)	Easy
205	Isomorphic Strings	C++ JAVA	Time - O(n) Space - O(1)	Easy
242	Valid Anagram	JAVA	Time - O(n) Space - O(1)	Easy
290	Word Pattern	JAVA	Time - O(n * m) Space - O(n)	Easy
344	Reverse String	C++ JAVA	Time - O(n) Space - O(1)	Easy
389	Find the Difference	C++ JAVA	Time - O(n) Space - O(1)	Easy
392	Is Subsequence	C++ JAVA	Time - O(n) Space - O(1)	Easy
409	Longest Palindrome	JAVA	Time - O(n) Space - O(n)	Easy
438	Find All Anagrams in a String	JAVA	Time - O(n) Space - O(n)	Medium
500	Keyboard Row	JAVA	Time - O(n) Space - O(n)	Easy
520	Detect Capital	C++ JAVA	Time - O(n) Space - O(1)	Easy
567	Permutation in String	C++ JAVA	Time - O(n) Space - O(1)	Medium
647	Palindromic Substrings	C++ JAVA	Time - O(n2) Space - O(1)	Medium
680	Valid Palindrome II	C++ JAVA	Time - O(n) Space - O(1)	Easy
796	Rotate String	C++ JAVA	Time - O(m * n) Space - O(1)	Easy
848	Shifting Letters	C++ JAVA	Time - O(n) Space - O(1)	Medium
1446	Consecutive Characters	C++ JAVA	Time - O(n) Space - O(1)	Easy
1461	Check If a String Contains All Binary Codes of Size K	JAVA	Time - O(n) Space - O(2k)	Medium
1528	Shuffle String	C++ JAVA	Time - O(n) Space - O(1)	Easy
1544	Make The String Great	C++ JAVA	Time - O(n) Space - O(1)	Easy
1662	Check If Two String Arrays are Equivalent	C++ JAVA	Time - O(n) Space - O(1)	Easy
1678	Goal Parser Interpretation	C++ JAVA	Time - O(n) Space - O(1)	Easy
1689	Partitioning Into Minimum Number Of Deci-Binary Numbers	JAVA	Time - O(n) Space - O(1)	Medium
1790	Check if One String Swap Can Make Strings Equal	C++ JAVA	Time - O(n) Space - O(1)	Easy
1769	Minimum Number of Operations to Move All Balls to Each Box	C++ JAVA	Time - O(n) Space - O(n)	Medium
1796	Second Largest Digit in a String	C++ JAVA	Time - O(n) Space - O(1)	Easy
1816	Truncate Sentence	C++ JAVA	Time - O(n) Space - O(1)	Easy
1844	Replace All Digits with Characters	C++ JAVA	Time - O(n) Space - O(1)	Easy
1903	Largest Odd Number in String	C++ JAVA	Time - O(n) Space - O(1)	Easy
1910	Remove All Occurrences of a Substring	C++ JAVA	Time - O(m * n) Space - O(n)	Medium
1945	Sum of Digits of String After Convert	C++ JAVA	Time - O(n) Space - O(1)	Easy
1941	Check if All Characters Have Equal Number of Occurrences	C++ JAVA	Time - O(n) Space - O(1)	Easy
2000	Reverse Prefix of Word	C++ JAVA	Time - O(n) Space - O(1)	Easy
2042	Check if Numbers Are Ascending in a Sentence	C++ JAVA	Time - O(n) Space - O(1)	Easy
2103	Rings and Rods	C++ JAVA	Time - O(n) Space - O(1)	Easy
1456	Maximum Number of Vowels in a Substring of Given Length	C++ JAVA	Time - O(n) Space - O(1)	Medium
2068	Check Whether Two Strings are Almost Equivalent	C++ JAVA	Time - O(n) Space - O(1)	Easy
2124	Check if All A's Appears Before All B's	C++ JAVA	Time - O(n) Space - O(1)	Easy
2129	Capitalize the Title	Explanation C++ JAVA	Time - O(n) Space - O(1)	Easy

Matrix

#	Title	Solution	Complexity	Difficulty	Tags
73	Set Matrix Zeroes	JAVA	Time - O(m * n) Space - O(m * n)	Easy	Array, HashTable
566	Reshape the Matrix	C++ JAVA	Time - O(m * n) Space - O(1)	Easy	Array, Simulation
867	Transpose Matrix	C++ JAVA	Time - O(m * n) Space - O(1)	Easy	Array, Simulation
1260	Shift 2D Grid	JAVA	Time - O(n) Space - O(1)	Easy	Array, Simulation
1572	Matrix Diagonal Sum	C++ JAVA	Time - O(n) Space - O(1)	Easy	Array
1582	Special Positions in a Binary Matrix	C++ JAVA	Time - O(m * n) Space - O(1)	Easy	Array

Hash Table

#	Title	Solution	Complexity	Difficulty	Tags
1	Two Sum	JAVA	Time - O(n) Space - O(n)	Easy	Array
49	Group Anagrams	JAVA	Time - O(n * m) Space - O(n)	Medium	String, Sorting
500	Keyboard Row	JAVA	Time - O(n) Space - O(n)	Easy	Array, String
1207	Unique Number of Occurrences	JAVA	Time - O(n) Space - O(n)	Easy	Array
1365	How Many Numbers Are Smaller Than the Current Number	C++ JAVA	Time - O(n + m) Space - O(m)	Easy	Array, Sorting, Counting
2053	Kth Distinct String in an Array	JAVA	Time - O(n) Space - O(n)	Easy	Array, String, Counting
2085	Count Common Words With One Occurrence	JAVA	Time - O(n + m) Space - O(n)	Easy	Array, String, Counting

Binary Search

#	Title	Solution	Complexity	Difficulty	Tags
33	Search in Rotated Sorted Array	C++ JAVA	Time - O(log2(n)) Space - O(1)	Medium	Array
74	Search a 2D Matrix	C++ JAVA	Time - O(log2(m * n)) Space - O(1)	Medium	Array, Matrix
153	Find Minimum in Rotated Sorted Array	C++ JAVA	Time - O(log2(n)) Space - O(1)	Medium	Array
162	Find Peak Element	C++ JAVA	Time - O(log2(n)) Space - O(1)	Medium	Array
704	Binary Search	C++ JAVA	Time - O(log2(n)) Space - O(1)	Easy	Array

Sorting

#	Title	Solution	Complexity	Difficulty
1365	How Many Numbers Are Smaller Than the Current Number	C++ JAVA	Time - O(n + m) Space - O(m)	Easy

Two Pointers

#	Title	Solution	Complexity	Difficulty
80	Remove Duplicates from Sorted Array II	C++ JAVA	Time - O(n) Space - O(1)	Medium

Dynamic Programming

#	Title	Solution	Complexity	Difficulty	Tags
70	Climbing Stairs	C++ JAVA	Time - O(n) Space - O(1)	Easy	Math, Memoization
264	Ugly Number II	C++ JAVA	Time - O(n) Space - O(n)	Medium	HashTable, Math, Heap(Priority Queue)
338	Counting Bits	C++ JAVA	Time - O(n) Space - O(n)	Easy	Bit Manipulation
1137	N-th Tribonacci Number	C++ JAVA	Time - O(n) Space - O(1)	Easy	Math, Memoization
1646	Get Maximum in Generated Array	C++ JAVA	Time - O(n) Space - O(n)	Easy	Array, Simulation