20,182,328 2019-2020-1 "Object-oriented programming and data structures," the tenth week learning summary

Learning content summary

FIGS by the vertices and edges.
Contiguous (adjacent): There is a communication in the edge between two vertices FIG.
Neighbors: adjacent vertices.
Since cyclic (ring): communicating a vertex and its own side.
Path by: a vertex reaches another apex.
The number of path sides (top units - 1): path length.
Loop: one kind of the same first and last vertex of the vertices and does not re-route side. No loop is acyclic (acyclic).

Undirected graph: a disordered edge nodes of FIG.
Complete: No side has the maximum number of vertices communication to FIG. For non-directed graph with n vertices, and if complete, there must be n (n-1) / 2 edges, assuming no edge is self-circulating.
Communication: there is no path to the FIG between any two vertices.
Undirected tree: No one kind of communication acyclic directed graph, in which an element is designated as the root.
Directed graph: also known as bi-directional picture, a drawing edge for the ordered pairs of vertices.
There is not a bidirectional path in the opposite direction does not hold to the road map.
Directed tree: Specifies an element as the root.
Root vertex to the other connection does not exist.
Each non-root exactly one connecting element.
Root vertex to each of the other has one path.
Network: Every edge with the right one kind or heavy expense FIG. Route weight is in the path of the edge weights and weight pieces.

Traversal
Breadth-first traversal: Similar to the tree hierarchy traversal. Each of the lateral abutment, traversing the FIG.
Depth-first traversal: As the name suggests, each of the adjacent longitudinal traverse FIG similar preorder traversal of the tree.
The only difference depth-first traversal and breadth-first traversal of the queue is used to manage the stack instead.
Test connectivity:
first traversal obtained starting from an arbitrary number of vertices equals the node number of vertices FIG contained, is connected.
Minimum spanning tree (minimum spanning tree): the edge weights equal to or less than the sum of the weights of any other edges and spanning tree.
Implementation strategies graph: adjacency list or adjacency matrix so on. A directed graph and an undirected graph are different.

Question 1: Tell the difference breadth-first traversal and depth-first traversal of the textbook, then step depth-first traversal of specifically what is it?
问题1解决方案：图的深度优先遍历和广度优先遍历的主要差异是它使用的是栈而不是队列来管理遍历的，所以步骤为从顶点9-->顶点6-->顶点3-->顶点1，到顶点1之后，再从顶点9的相邻顶点开始重新遍历。
问题2：有向图和无向图的邻接矩阵有什么区别?
问题2解决方案：

一、对称区别：

1、无向图的邻接矩阵是对称的。

2、有向图的邻接矩阵不一定对称。

二、元素区别：

1、对于无向图，顶点V1的度是邻接矩阵中第i行（或第i列）的非零元素的个数。

2、对于有向图，顶点V1的度是邻接矩阵中第i行和第i列的非零元素的个数之和。

本周虽然只学了一章，但图在数据结构中应用范围是较为广泛的，实现的方法也是多种多样。要想全部理解吸收还是很有难度的，但是努力的敲课本上的代码，再加上从网上搜资料还是能够解决问题的。

	代码行数（新增/累积）	博客量（新增/累积）	学习时间（新增/累积）
目标	5000行	30篇	400小时
第一周	200/200	2/2	20/20
第二周	300/500	2/4	18/38
第三周	500/1000	3/7	22/60
第四周	300/1300	2/9	30/90

尝试一下记录「计划学习时间」和「实际学习时间」，到期末看看能不能改进自己的计划能力。这个工作学习中很重要，也很有用。
耗时估计的公式：Y=X+X/N ，Y=X-X/N，训练次数多了，X、Y就接近了。