原创 Inorder Successor in BST II

Given a node in a binary search tree, find the in-order successor of that node in the BST. If that node has no in-order

2020-07-07 03:55:24 1

原创 Sorting (Merge Sort, Rainball Sort, quick select) 總結

Merge k Sorted Lists (這題是用PQ，或者merge sort都可以做，關於第K大的問題，參考: Find Kth 題目類型總結) Sort an Array (重點掌握merge sort和quick sort，因爲

2020-07-05 19:55:26

原创 Math 題目總結

Math的題目，其實全是數學知識，沒有什麼太多的算法可言。 Sparse Matrix Multiplication (矩陣相乘就是所有的k，A(i,k) * B(k,j) = C(i,j) ，稀疏矩陣就是 有很多0，爲了提高速度也就是如

2020-07-04 13:47:03

原创 記憶化搜索總結

Longest Increasing Path in a Matrix dp[i][j] 代表的是以i,j爲index的cell，最長的升序長度是多少。然後每個點做dfs，判斷四個方向的來的最大值；Time O(M*N) Space: O

2020-07-04 13:47:03

原创 BFS 到 Level Order traverse 到 UnionFind 到 Topological Sort 到 Dijkstra 思路總結

BFS 找聯通量,找component. Number of Islands (BFS, DFS 都可以做) Surrounded Regions (BFS, DFS都可以做)   Union Find 找聯通量是最合適的方法：對於動態加

2020-07-02 14:45:29 1

原创 Maximum Points You Can Obtain from Cards

There are several cards arranged in a row, and each card has an associated number of points The points are given in the

2020-07-01 00:20:30

原创 Maximum of Absolute Value Expression

Given two arrays of integers with equal lengths, return the maximum value of: |arr1[i] - arr1[j]| + |arr2[i] - arr2[j]|

2020-07-01 00:20:30

原创 Swap Adjacent in LR String

In a string composed of 'L', 'R', and 'X' characters, like "RXXLRXRXL", a move consists of either replacing one occurre

2020-07-01 00:20:30

原创 Android Unlock Patterns

Given an Android 3x3 key lock screen and two integers m and n, where 1 ≤ m ≤ n ≤ 9, count the total number of unlock pa

2020-07-01 00:20:30

原创 Bricks Falling When Hit

We have a grid of 1s and 0s; the 1s in a cell represent bricks.  A brick will not drop if and only if it is directly co

2020-07-01 00:20:30

原创 Most Stones Removed with Same Row or Column

On a 2D plane, we place stones at some integer coordinate points.  Each coordinate point may have at most one stone. No

2020-07-01 00:20:19

原创 Jump Game IV

Given an array of integers arr, you are initially positioned at the first index of the array. In one step you can jump

2020-07-01 00:20:19

原创 Minimum Number of Taps to Open to Water a Garden

There is a one-dimensional garden on the x-axis. The garden starts at the point 0 and ends at the point n. (i.e The len

2020-07-01 00:20:19

原创 Encode String with Shortest Length

Given a non-empty string, encode the string such that its encoded length is the shortest. The encoding rule is: k[encod

2020-07-01 00:20:19 1

原创 Minimum Distance to Type a Word Using Two Fingers

You have a keyboard layout as shown above in the XY plane, where each English uppercase letter is located at some coor

2020-07-01 00:20:19