计算机二级判断题必背知识点2022（计算机二级必备干货）

计算机二级判断题必背知识点2022（计算机二级必备干货）1. Characteristics of the algorithmAn algorithm is an accurate and complete description of a problem solution.001.算法算法是指解题方案的准确而完整的描述法。1．算法的特征①可行性：基本运算必须执行有限次来实现。②确定性：算法的每一步都是明确的，都必须有明确定义，不能有模棱两可的解释。③有穷性：算法必须能在有限的时间内做完。④输入与输出：一个算法有0个或多个输入，有一个或多个输出。2．算法的基本组成要素①数据对象的运算和操作：包括算术运算、逻辑运算、关系运算和数据传输（赋值、输入和输出）等。②算法的控制结构：即算法各操作步骤之间的执行顺序，一般是由顺序结构、选择结构（或分支结构）、循环结构三种基本结构组合而成的。3．算法复杂度①算法的时间复杂度：指执行算法所需要的运算次数或工作量

计算机二级必备干货——选择题基础知识（1）

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数据结构与算法

001.算法

算法是指解题方案的准确而完整的描述法。
1．算法的特征
①可行性：基本运算必须执行有限次来实现。
②确定性：算法的每一步都是明确的，都必须有明确定义，不能有模棱两可的解释。
③有穷性：算法必须能在有限的时间内做完。
④输入与输出：一个算法有0个或多个输入，有一个或多个输出。
2．算法的基本组成要素
①数据对象的运算和操作：包括算术运算、逻辑运算、关系运算和数据传输（赋值、输入和输出）等。
②算法的控制结构：即算法各操作步骤之间的执行顺序，一般是由顺序结构、选择结构（或分支结构）、循环结构三种基本结构组合而成的。
3．算法复杂度
①算法的时间复杂度：指执行算法所需要的运算次数或工作量。
②算法的空间复杂度；指执行这个算法所需要的存储空间。
二者之间没有直接关系。

001. The algorithm

An algorithm is an accurate and complete description of a problem solution.

1. Characteristics of the algorithm

① Feasibility: Basic operations must be performed a limited number of times to achieve.

② Certainty: each step of the algorithm is clear must be clearly defined can not be ambiguous interpretation.

(3) Fineness: the algorithm must be able to finish in a limited time.

④ Input and output: an algorithm has zero or more inputs with one or more outputs.

2. The basic elements of an algorithm

① Operation and operation of data objects: including arithmetic operation logical operation relational operation and data transmission (assignment input and output) etc.

(2) Control structure of the algorithm: that is the execution order of the algorithm between the operation steps is generally composed of sequence structure selection structure (or branch structure) circular structure of three basic structures.

3. Algorithm complexity

① Time complexity of the algorithm: refers to the number of operations or workload needed to execute the algorithm.

(2) The spatial complexity of the algorithm; Refers to the amount of storage required to perform the algorithm.

There is no direct relationship between the two.

002．数据结构

数据结构指数据在计算机中如何表示、存储、管理，各数据元素之间具有怎样的关系、怎样互相运算等。
1．数据结构分类
①逻辑结构：各数据元素之间所固有的前后逻辑关系（与存储位置无关）。
②存储结构：指数据的逻辑结构在计算机中的表示和存放形式。包含顺序存储和链式存储，链式存储可以使数据插入和删除的效率更高。
2．线性结构和非线性结构
①线性结构：即各数据元素具有“一对一”关系的数据结构，包括数组、线性链表、栈、队列等。
线性结构的条件：
a.有且只有一个根结点：
b.每一个结点最多有一个前件，也最多有一个后件。
②非线性结构：前后件的关系是“一对多”或“多对多”，包括二维数组、多维数组、广义表、树（二叉树）、图等。

002. The data structure

Data structure index data in the computer how to represent store management the relationship between data elements how to operate with each other.

1. Data structure classification

(1) Logical structure: the inherent before and after logical relationship between each data element (independent of storage location).

② Storage structure: the representation and storage form of the logical structure of the data in the computer. Includes sequential storage and chained storage which makes data insertion and deletion more efficient.

2. Linear structure and nonlinear structure

① Linear structure: that is each data element has a "one-to-one" relationship of data structure including array linear linked list stack queue etc.

Conditions for linear structures:

A. Have one and only one root:

B. Each node has at most one precursor and at most one aftercomponent.

② Nonlinear structure: before and after the relationship is "one-to-many" or "many-to-many" including two-dimensional array multidimensional array generalized table tree (binary tree) graph etc.

003.线性表

线性表是最简单、最常用的一种数据结构，线性表是一种线性结构。
1．非空线性表的结构特征
①有且只有一个根结点，它无前件。
②有且只有一个终端结点，它无后件。
③除根结点与终端结点外，其他所有结点有且只有一个前件，也有且只有一个后件。线性表中结点的个数n称为线性表的长度。当n＝0时，称为空表。
2．线性表的顺序存储结构特点
①线性表中所有元素所占的存储空间是连续的。
②线性表中各数据元素在存储空间中是按逻辑顺序依次存放的。

003. The linear table

Linear table is the simplest and most commonly used data structure and linear table is a linear structure.

1. Structural characteristics of nonempty linear tables

① There is one and only one root node which has no precursor.

② There is only one terminal node which has no afterware.

③ Except the root node and terminal node all other nodes have only one antecedent and only one aftercomponent. The number of nodes in a linear table n is called the length of a linear table. When n = 0 it is called an empty table.

2. Sequential storage structure characteristics of linear tables

① The storage space occupied by all elements in a linear table is continuous.

② Each data element in a linear table is stored in logical order in the storage space.

004．线性链表

线性链表是线性表的链式存储结构，简称链表。
链表相比顺序表优点：
①链表在插入或删除运算中不用移动大量数据元素，因此运算效率高。
②链表存储空间可以动态分配并易于扩充。

004. Linear list

Linear linked list is the chain storage structure of linear list referred to as linked list.

Advantages of linked lists over sequential lists:

① The linked list does not need to move a large number of data elements in the operation of insertion or deletion so the operation efficiency is high.

② Linked list storage space can be dynamically allocated and easily expanded.

005．查找技术

1．顺序查找
长度为n的线性表，查找一个数据最坏需查找n次，平均需要查找n 1/2;
长度为n的线性表，查找最大（最小）值需查找n-1次。
2．二分法查找
二分法查找也称对分查找，它只适用于顺序存储结构的有序线性表，且该有序线性表的数据元素按值非递减排列（即从小到大，但允许相邻元素相等）。
在最坏情况下，二分法查找只需要查找log2n次。

005. Search technology

1. In order to find

For a linear table of length N the search for a data is at worst n times and the average search is n 1/2;

For a linear table of length N find the maximum (minimum) value n-1 times.

2. Binary search

Dichotomy search also known as logarithmic search applies only to ordered linear tables with sequential storage structures and the data elements of the ordered linear table are arranged in non-decreasing order of value (that is from small to large but adjacent elements are allowed to be equal).

In the worst case a dichotomous lookup only requires a lookup log_2⁡n times.

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参考资料：百度百科、谷歌翻译。

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