Algorithm on Lotp's Blog

[LeetCode 233, AC] Number of Digit One Done With DP

Mon, 25 May 2020 19:39:16 +0000

Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.

Example:

Input: 13
Output: 6 
Explanation: Digit 1 occurred in the following numbers: 1, 10, 11, 12, 13.

Let’s try to solve this problem by dividing it into smaller quizzes:

For example, to caculate the result for 2954:

count(2954)=count(2000)+count(954)
count(954)=count(900)+count(54)
count(54)=count(50)+count(4)

Now we got the conclusion that count(2954)=count(2000)+count(900)+count(50)+count(4), which is leading us to the question of how to get count(i*10^j)

[LeetCode 455, AC] Assign Cookies

Sat, 10 Dec 2016 01:49:42 +0000

Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a cookie that the child will be content with; and each cookie j has a size sj. If sj >= gi, we can assign the cookie j to the child i, and the child i will be content. Your goal is to maximize the number of your content children and output the maximum number.

[LeetCode 126, TLE] Word Ladder II

Sat, 26 Nov 2016 09:39:16 +0000

If you come here for a solution to the problem, you are in a wrong place. Because my code for this quiz wasn’t accepted yet and the purpose of this post is to make a summary about what I have learnt about BFS from doing this exercise. I will share my code at the end of this post and any ideas on where my code is wrong would be greatly appreciated.