I had the same BFS idea as one of the AC code this: because dying pattern is spead from the initial dying ones :) #include <iostream> #include <queue> #include <vector> using namespace std; int main() { int N; cin >> N; vector<,…

题目传送门:https://www.hackerrank.com/challenges/unique-colors 感谢hzq大神找来的这道题. 考虑点分治(毕竟是路经统计),对于每一个颜色,它的贡献是独立的.我们可以在一次点分治中合在一块处理(为什么时间复杂度是对的呢,因为我们每次改动只会根据当前点的颜色进行变动,而不是所有颜色对着它都来一遍).每次先对重心单独计算答案贡献,此时也将当前区域的各个答案贡献计算出来,并以此为基础(之后称之为基准贡献,即代码中的tot).对于每一棵子树,我们先df…

Firt thought: an variation to LCS problem - but this one has many tricky detail. I learnt the solution from this link:https://github.com/wangyongliang/Algorithm/blob/master/hackerrank/Strings/Square%20Subsequences/main.cc And here is his code with my…

It is about how to choose btw. BFS and DFS. My init thought was to DFS - TLE\MLE. And its editorial gives a very neat BFS based idea which costs much less memory. https://www.hackerrank.com/challenges/beautiful-path/editorial…

It is marked as a NPC problem. However from the #1 code submission (https://www.hackerrank.com/CharlesOfria), it looks pretty much like a Brutal-Force (or simulation) based solution, mixed with some greedy strategies. To me the other NPC "Queens Revi…

传送门 今天在HackerRank上翻到一道高精度题,于是乎就写了个高精度的模板,说是模板其实就只有乘法而已. Extra long factorials Authored by vatsalchanana on Jun 16 2015 Problem Statement You are given an integer N. Print the factorial of this number. N!=N×(N−1)×(N−2)×⋯×3×2×1 Note: Factorials of N>20…

Great learning for me:https://www.hackerrank.com/rest/contests/master/challenges/lucky-numbers/hackers/turuthok/download_solution Basically it is memorized search application. And we follow a discrete strategy: split it into digits and go digit by di…

This is 'Difficult' - I worked out it within 45mins, and unlocked HackerRank Algorithm Level 80 yeah! So the idea is straight forward: 1. sort the input array and calculate partial_sum()2. find the negative\positive boundary with the accumulated give…

A sly knapsack problem in disguise! Thanks to https://github.com/bhajunsingh/programming-challanges/tree/master/hackerrank/algorithms/the-indian-jobLesson learnt: The Italian\Indian job is two-way 01 Knapsack. And some complext problem can be convert…

The most interesting, flexible and juicy binary tree problem I have ever seen. I learnt it from here: https://codepair.hackerrank.com/paper/5fIoGg74?b=eyJyb2xlIjoiY2FuZGlkYXRlIiwibmFtZSI6IkJsdWVCaXJkMjI0IiwiZW1haWwiOiJoZWFsdGh5dG9ueUBnbWFpbC5jb20ifQ%…