刷题记录帖子

453. Minimum Moves to Equal Array Elements

len*(min+k)=sum+k*(len-1). ==> k=sum-min*len

462. Minimum Moves to Equal Array Elements II

This problem is deceptive in its simplicity. Ultimately, the value to which you want to set each element equal is the median of the sorted nums array. To come to this realization, we have to first think about the nature of the problem.

Let's consider a possible scenario in which we've decided that our target value is x which would take ans number of moves to complete. What would happen to ans if we increased x by 1? If we did, each element that is below the new x would have to spend another move to get up to x, but every element that is above the new x would have to spend one less move to get down to x.

This means that x should naturally move up if there are more elements above x than below. It also means the inverse, that x should move down if there are more elements below x than above. The natural outcome of this is that x will settle at a spot where there are the same number of elements on either side, which is the median value of nums.

https://leetcode.com/problems/mi ... ution-w-Explanation

102. Binary Tree Level Order Traversal

之前写过，这次 3 min 解决，给自己加个油，功不唐捐。

890        Find and Replace Pattern        Medium        5        Two Maps CrossCheck / One Map FingerPrint

485        Max Consecutive Ones

Easy 但是需要知道如何简洁地得到 code。

                               
414        Third Maximum Number        Easy        4        set, sort, a[-3] for third max

263        Ugly Number        Easy        3        Definiation of ugly number

LC 197

SQL to remember how to do

1. 
   
2. 
   
3. # Write your MySQL query statement below
   
4. SELECT
   
5.     weather.id AS 'id'
   
6. FROM
   
7.     weather
   
8.         JOIN
   
9.     weather w ON DATEDIFF(weather.recordDate, w.recordDate) = 1
   
10.         AND weather.Temperature > w.Temperature
    
11. ;
    
12. 
    

复制代码

118        Pascal's Triangle        Easy

LeetCode 150. Evaluate Reverse Polish Notation (Python)

原理理解了，这里好多 Python 的细节考察啊！～

How to round to Zero + How to get Python string a number either postive or negative