Leetcode questions from 61 - 69

August 21, 2015

Speed up study leetcode questions, 10 question a time, in 2-3 hours. And see if I can learn something quickly.

61 Rotate List

http://bangbingsyb.blogspot.ca/2014/11/leetcode-rotate-list.html

julia's C# implementation practice:
https://github.com/jianminchen/Leetcode_C-/blob/master/61RotateList.cs

62 Unique Paths

http://bangbingsyb.blogspot.ca/2014/11/leetcode-unique-paths-i-ii.html

http://siddontang.gitbooks.io/leetcode-solution/content/dynamic_programming/unique_paths.html

http://yucoding.blogspot.ca/2013/04/leetcode-question-116-unique-path-i.html

DP algorithm in detail, time complexity and space complexity analysis is great in the following blog:

http://codeganker.blogspot.ca/2014/03/unique-paths-leetcode.html

63 Unique Paths II

64 Minimum Path Sum

discussion of using 2 dimension array or using one dimension array, still not clear.

http://fisherlei.blogspot.ca/2012/12/leetcode-minimum-path-sum.html

understand this blog on DP solutions, one is space O(n^2), one is space O(n).

http://joycelearning.blogspot.ca/2013/10/leetcode-minimum-path-sum.html

http://shanjiaxin.blogspot.ca/2014/03/minimum-path-sum-leetcode.html

65 Valid number

ideas for the solution from the following blog: 

3 flags are set: num, exp, dot, and then,

1. if there is e flag, then there is a digit before e flag, cannot have any e.

Also, there is a digit followed.

2. if . shows up, then it is a small fraction number, so neither . nor e is before .

3. if +, -, then it must be first one, or the previous on is e,

for example: "005047e+6".

The above summary is from the following blog:

http://www.yanyulin.info/pages/2014/10/38958011441714.html

code is here:

http://www.jiuzhang.com/solutions/valid-number/

Julia's C# code practice:

https://github.com/jianminchen/Leetcode_C-/blob/master/65ValidNumber.cs

blogs:
https://leetcodenotes.wordpress.com/2013/11/23/leetcode-valid-number/
http://www.cnblogs.com/TenosDoIt/p/3475305.html
http://www.cnblogs.com/chasuner/p/validNumber.html
https://github.com/fuwutu/LeetCode/blob/master/Valid%20Number.cpp

http://rleetcode.blogspot.ca/2014/01/valid-number-java.html

66 Plus number

67 Add Binary

Totally forget I did this implementation. So, I have to learn everything about this problem again, read more blogs this time.

https://github.com/jianminchen/addBinary/blob/master/Program.cs

my favorite solution is the following blog:
http://fisherlei.blogspot.ca/2013/01/leetcode-add-binary.html

julia's C# code:
https://github.com/jianminchen/Leetcode_C-/blob/master/67AddBinary2.cs

http://bangbingsyb.blogspot.ca/2014/11/leetcode-add-binary.html

the code should be more short, but the discussion and idea in the code is very clear.
http://siddontang.gitbooks.io/leetcode-solution/content/string/add_binary.html

Good quality code, try it myself later.
http://www.jiuzhang.com/solutions/add-binary/

julia's c# implementation:
https://github.com/jianminchen/Leetcode_C-/blob/master/67AddBinary.cs

68 Text Justification

69 sqrt(x)

http://yucoding.blogspot.ca/2013/03/leetcode-question-102-sqrtx.html

http://codeganker.blogspot.ca/2014/02/sqrtx-leetcode.html

C# implementation:
https://github.com/jianminchen/Leetcode_C-/blob/master/69Sqrt(x).cs

70 Climbing Stairs

http://juliachencoding.blogspot.ca/2015/07/leetcode-climbing-stairs.html