寒冻不改少年心，编程热情破冰岩

——2025年寒假训练题单

Cold doesn't change young people's hearts, programming passion breaks through ice rock

——2025 Winter Vacation Training Question Sheet

本次题目共28题，由洛谷部分、CF部分和ACGO部分组成，分为入门题目、提高题目和挑战题目。含*的题目是选做题，有时间推推思路即可。

There are a total of 28 questions in this session, consisting of the Luogu section, CF section, and ACGO section, which are divided into introductory questions, improvement questions, and challenge questions. Questions containing * are multiple-choice questions, and if you have time, you can deduce your thoughts.

本期特训专题为：深度优先搜索的枚举。

This special training topic is: Enumeration of Depth First Search.

洛谷部分

Luogu's Part

入门题目（Introduction topic）：B2015、B2019、B2084、P1909、P1055、P1138

提高题目（Improve the topic）：P1720、P1601、P1616*

挑战题目（Challenge Question）：P1236*

CodeForces部分

CodeForces' Part

入门题目（Introduction topic）：16A、16B、22A、26A、61A、59A

提高题目（Improve the topic）：25A、18A、13A*

挑战题目（Challenge Question）：7C*

ACGO部分

ACGO's Part

特训题目（Special training topic）：A150、A27003、A164、A21628、A30929、A8*