CNoodle

[LeetCode] 1358. Number of Substrings Containing All Three Characters

Given a string s consisting only of characters a, b and c. Return the number of substrings containing at least one occurrence of all these characters a, b and c. Example 1:Input: s = “abcabc”Outp

2020-12-24

#leetcode #java #two pointer #hashmap #sliding window #string

[LeetCode] 1020. Number of Enclaves

You are given an m x n binary matrix grid, where 0 represents a sea cell and 1 represents a land cell. A move consists of walking from one land cell to another adjacent (4-directionally) land cell or

2020-12-22

#leetcode #bfs #dfs #java #flood fill

[LeetCode] 921. Minimum Add to Make Parentheses Valid

A parentheses string is valid if and only if: It is the empty string, It can be written as AB (A concatenated with B), where A and B are valid strings, or It can be written as (A), where A is a valid

2020-12-18

#leetcode #java #greedy #stack

[LeetCode] 1669. Merge In Between Linked Lists

You are given two linked lists: list1 and list2 of sizes n and m respectively. Remove list1’s nodes from the ath node to the bth node, and put list2 in their place. The blue edges and nodes in the fol

2020-12-15

#leetcode #java #linked list

[LeetCode] 1609. Even Odd Tree

A binary tree is named Even-Odd if it meets the following conditions:The root of the binary tree is at level index 0, its children are at level index 1, their children are at level index 2, etc.For ev

2020-12-10

#leetcode #tree #bfs #java

[LeetCode] 1325. Delete Leaves With a Given Value

Given a binary tree root and an integer target, delete all the leaf nodes with value target. Note that once you delete a leaf node with value target, if its parent node becomes a leaf node and has the

2020-12-02

#leetcode #tree #java #postorder #recursion

[LeetCode] 814. Binary Tree Pruning

Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed. A subtree of a node node is node plus every node that is a descendant

2020-12-02

#leetcode #tree #java #postorder

[LeetCode] 1010. Pairs of Songs With Total Durations Divisible by 60

You are given a list of songs where the ith song has a duration of time[i] seconds. Return the number of pairs of songs for which their total duration in seconds is divisible by 60. Formally, we want

2020-11-28

#leetcode #java #array #hashmap #two sum #counting sort #MOD

[LeetCode] 395. Longest Substring with At Least K Repeating Characters

Given a string s and an integer k, return the length of the longest substring of s such that the frequency of each character in this substring is greater than or equal to k. if no such substring exist

2020-11-27

#leetcode #java #hashmap #sliding window #string #divide and conquer

[LeetCode] 1404. Number of Steps to Reduce a Number in Binary Representation to One

Given the binary representation of an integer as a string s, return the number of steps to reduce it to 1 under the following rules:If the current number is even, you have to divide it by 2.If the cur

2020-11-23

#leetcode #java #string #bit manipulation