## [cf1610G]AmShZ Wins a Bet

The operation on $t $inserts a pair of parentheses in $t $, and the reverse process deletes a pair of parentheses
In other words, $s $can be obtained by $t $if and only if $t $can be obtained by deleting several pairs of parentheses in $s $, that is, the problem is to find $\ min t$
Conclusion $\ min t can be obtained by deleting several legiti ...

Posted by **Zilvermeeuw** on *Fri, 03 Dec 2021 09:15:53 -0800*

## [CF1007D] Ants (tree chain subdivision + 2-SAT)

Click here to see the problem
There is a tree with \ (n \) points.
You need to perform \ (m \) coloring operations. Each operation gives two point pairs \ ((x_1,y_1) \) and \ ((x_2,y_2) \), and you need to select a point pair to color all the edges in the path on the corresponding tree. It is required that the same edge cannot be dyed repeated ...

Posted by **Andrei** on *Thu, 04 Nov 2021 10:57:34 -0700*

## Codeforces Round #753 (Div. 3)

There are three main situations:
It's been a second since I took a look at my beard. The implementation is also very simple. I write casually / too lazy to write
After a second, I felt that it would not be realized, so I went to look at other people's code
I didn't understand the question
A
Direct simulation.
B
Simple math problems + find rul ...

Posted by **morris** on *Wed, 03 Nov 2021 17:48:13 -0700*

## Codeforces Round #751 (Div. 2)(A - C)

A.Two Subsequences
Topic Essentials
Give you a string s. You need to find two non-empty strings a and b to satisfy the following conditions: (1) Strings a and b are subsequences of s. (2) For each index i, the character s [i] in the string s must exactly belong to one of the strings a or b. (3) String a is the smallest possible dictionary ...

Posted by **rash** on *Sun, 31 Oct 2021 11:33:25 -0700*

## Codeforces Round #752 (Div. 2) A B C D

Codeforces Round #752 (Div. 2)
Record high!!
A. Era
Idea: at first, I thought it was to find a maximum subscript, and then output the maximum minus the maximum subscript. Later, I dropped this idea with the data 1 1 5 1 6 hack, and it was obvious that as long as I enumerated it, I saved the largest memory
...

Posted by **jaybeeb** on *Sat, 30 Oct 2021 11:24:42 -0700*

## [2021-9-23] supplementary question record

Educational Codeforces Round 54 (Rated for Div. 2) E. Vasya and a Tree Main idea of the topic: given a tree with 1 as the root node, each node value is 0, given several modifications, x,d,v, is the y value of X node and its dist (x, y) < = D, plus v, and finally outputs the value of each node; Solution: for offline modification, use the tree ...

Posted by **daniel_lee_hill** on *Thu, 23 Sep 2021 01:05:23 -0700*