Adjacency matrix non-direction diagram (a) C language detailed

An introduction to the non-direction graph of adjacency matrices

The non-direction graph of adjacency matrix refers to the graph represented by adjacency matrix.

The above figure G1 contains "a,b,c,d,e,f,g" a total of 7 vertices, and contains "(A,c), (A,d), (a,f), (B,c), (C,d), (E,g), (f,g)" A total of 7 sides. Since this is a a,c graph, the edges (c,a) and sides (the edges) are the same; the edges are enumerated in alphabetical order.

The matrix on the right of the above figure is a schematic diagram of the adjacency matrix in memory of the G1. The a[i][j]=1 indicates that the vertex I and the J Vertex are adjacent points, a[i][j]=0 means that they are not adjacency points, whereas A[i][j] represents the value of the J column of line I, for example, a[1,2]=1, which means that the 1th vertex (i.e. vertex b) and 2nd vertex (C) are contiguous points.

Code description of the adjacency matrix non-direction graph

1. Basic definition

The adjacency matrix
typedef struct _GRAPH
{
    char vexs[max];       Vertex set
    int vexnum;           Vertex number
    int edgnum;           Number of edges
    int Matrix[max][max];//adjacency Matrix
}graph, *pgraph;

Graph is the corresponding structure of adjacency matrix.
Vexs is used to save vertices, Vexnum is the number of vertices, edgnum is the number of edges, and matrix is a two-dimensional array to hold the information of matrices. For example, matrix[i][j]=1, which means "vertex I (i.e. vexs[i])" and "Vertex J (i.e. Vexs[j])" are adjacency points, and matrix[i][j]=0 means that they are not adjacency points.

2. Create a matrix

This provides two ways to create matrices. One is with known data , and the other requires the user to enter data manually .

2.1 Creating the diagram (with the provided matrix)

 * * * Create diagram (with provided matrix)/graph* create_example_graph () {char vexs[] = {' A ', ' B ', ' C ', ' D ', ' E ', ' F ', ' G '}; Char edges[][2] = {' A ', ' C '}, {' A ', ' d '}, {' A ', ' F '}, {' B ', ' C '}, {' C ', ' d '} 
    , {' E ', ' g '}, {' F ', ' G '}};
    int vlen = LENGTH (Vexs);
    int Elen = LENGTH (edges);
    int I, p1, p2;
    
    graph* PG;
    Enter "vertex number" and "number of edges" if ((pg= (graph*) malloc (sizeof (Graph)) = = null) return null;
    
    memset (PG, 0, sizeof (Graph));
    Initialize "vertex number" and "number of edges" pg->vexnum = Vlen;
    Pg->edgnum = Elen;
    Initializes "vertex" for (i = 0; i < pg->vexnum; i++) {pg->vexs[i] = vexs[i]; }//Initialize "Edge" for (i = 0; i < pg->edgnum; i++) {//read edge start vertex and end vertex P1 = get_position (*
        PG, edges[i][0]);
    
        P2 = get_position (*PG, edges[i][1]);
        PG->MATRIX[P1][P2] = 1;
    PG->MATRIX[P2][P1] = 1;
} return PG; }

CreateExamplegraph is the function of creating an adjacency matrix without direction graph.

Note: This method creates a G1 graph, which is the diagram above.

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