LeetCode problem 992 Subarrays with K Different Integers (Java)

Source url: https://leetcode.com/problems/subarrays-with-k-different-integers/

Given an array A of positive integers, call a (contiguous, not necessarily distinct) subarray of A good if the number of different integers in that subarray is exactly K.

(For example, [1,2,3,1,2] has 3 different integers: 12, and 3.)

Return the number of good subarrays of A.

Example 1:

Input: A = [1,2,1,2,3], K = 2
Output: 7
Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2].

Example 2:

Input: A = [1,2,1,3,4], K = 3
Output: 3
Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].


  1. 1 <= A.length <= 20000
  2. 1 <= A[i] <= A.length
  3. 1 <= K <= A.length
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LeetCode problem 567 Permutation in String (Java)


Given two strings s1 and s2, write a function to return true if s2 contains the permutation of s1. In other words, one of the first string’s permutations is the substring of the second string.

Example 1:

s1 = “ab”
s2 = “eidbaooo”
Output: True
Explanation: s2 contains one permutation of s1 (“ba”).

Example 2:

s1= “ab”
s2 = “eidboaoo”
Output: False


  1. The input strings only contain lower case letters.
  2. The length of both given strings is in the range [1, 10,000].
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LeetCode problem 438 Find All Anagrams in a String (Java)

Source url: https://leetcode.com/problems/find-all-anagrams-in-a-string/

Given a string s and a non-empty string p, find all the start indices of p‘s anagrams in s.

Strings consists of lowercase English letters only and the length of both strings s and p will not be larger than 20,100.

The order of output does not matter.

Example 1:

s: “cbaebabacd”
p: “abc”
Output: [0, 6]
The substring with start index = 0 is “cba”, which is an anagram of “abc”.
The substring with start index = 6 is “bac”, which is an anagram of “abc”.

Example 2:

s: “abab”
p: “ab”
Output: [0, 1, 2]
The substring with start index = 0 is “ab”, which is an anagram of “ab”.
The substring with start index = 1 is “ba”, which is an anagram of “ab”.
The substring with start index = 2 is “ab”, which is an anagram of “ab”.

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LeetCode problem 424 Longest Repeating Character Replacement(Java)

Source Url:https://leetcode.com/problems/longest-repeating-character-replacement/

Given a string that consists of only uppercase English letters, you can replace any letter in the string with another letter at most k times. Find the length of a longest substring containing all repeating letters you can get after performing the above operations.

Both the string’s length and k will not exceed 104.

Example 1:

Input: s = “ABAB”, k = 2
Output: 4
Explanation: Replace the two ‘A’s with two ‘B’s or vice versa.

Example 2:

Input: s = “AABABBA”, k = 1
Output: 4
Explanation: Replace the one ‘A’ in the middle with ‘B’ and form “AABBBBA”. The substring “BBBB” has the longest repeating letters, which is 4.

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LeetCode Problem 30 Substring with Concatenation of All Words (Java)

Source url:https://leetcode.com/problems/substring-with-concatenation-of-all-words/

You are given a string, s, and a list of words, words, that are all of the same lengths. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.

Example 1:

Input: s = “barfoothefoobarman”, words = [“foo”,”bar”]
Output: [0,9]
Explanation: Substrings starting at index 0 and 9 are “barfoor” and “foobar” respectively. The output order does not matter, returning [9,0] is fine too.

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LeetCode 3. Longest Substring Without Repeating Characters (Java)

Soure Urlhttps://leetcode.com/problems/longest-substring-without-repeating-characters/

Given a string, find the length of the longest substring without repeating characters.

Example 1:
Input: “abcabcbb”
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2:
Input: “bbbbb”
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:
Input: “pwwkew”
Output: 3
Explanation: The answer is "wke", with the length of 3.
Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

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Leetcode 2 Add Two Numbers (Java)

Source Url:https://leetcode.com/problems/add-two-numbers/


You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contains a single digit. Add the two numbers and return it as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

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Where is Sri Lanka?

Sri Lanka officially the Democratic Socialist Republic of Sri Lanka is an island country in South Asia, located in the Indian Ocean to the southwest of the Bay of Bengal and the southeast of the Arabian Sea. The island is geographically separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. The legislative capital, Sri Jayawardenepura Kotte, is a suburb of the commercial capital and largest city, Colombo.

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