103 lines
2.8 KiB
Go
103 lines
2.8 KiB
Go
// File: graph_adjacency_matrix.go
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// Created Time: 2023-01-31
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// Author: Reanon (793584285@qq.com)
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package chapter_graph
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import "fmt"
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/* Undirected graph class based on adjacency matrix */
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type graphAdjMat struct {
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// Vertex list, elements represent "vertex value", index represents "vertex index"
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vertices []int
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// Adjacency matrix, row and column indices correspond to "vertex index"
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adjMat [][]int
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}
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/* Constructor */
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func newGraphAdjMat(vertices []int, edges [][]int) *graphAdjMat {
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// Add vertex
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n := len(vertices)
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adjMat := make([][]int, n)
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for i := range adjMat {
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adjMat[i] = make([]int, n)
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}
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// Initialize graph
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g := &graphAdjMat{
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vertices: vertices,
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adjMat: adjMat,
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}
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// Add edge
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// Please note, edges elements represent vertex indices, corresponding to vertices elements indices
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for i := range edges {
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g.addEdge(edges[i][0], edges[i][1])
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}
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return g
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}
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/* Get the number of vertices */
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func (g *graphAdjMat) size() int {
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return len(g.vertices)
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}
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/* Add vertex */
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func (g *graphAdjMat) addVertex(val int) {
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n := g.size()
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// Add new vertex value to the vertex list
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g.vertices = append(g.vertices, val)
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// Add a row to the adjacency matrix
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newRow := make([]int, n)
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g.adjMat = append(g.adjMat, newRow)
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// Add a column to the adjacency matrix
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for i := range g.adjMat {
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g.adjMat[i] = append(g.adjMat[i], 0)
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}
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}
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/* Remove vertex */
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func (g *graphAdjMat) removeVertex(index int) {
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if index >= g.size() {
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return
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}
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// Remove vertex at `index` from the vertex list
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g.vertices = append(g.vertices[:index], g.vertices[index+1:]...)
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// Remove the row at `index` from the adjacency matrix
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g.adjMat = append(g.adjMat[:index], g.adjMat[index+1:]...)
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// Remove the column at `index` from the adjacency matrix
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for i := range g.adjMat {
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g.adjMat[i] = append(g.adjMat[i][:index], g.adjMat[i][index+1:]...)
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}
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}
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/* Add edge */
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// Parameters i, j correspond to vertices element indices
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func (g *graphAdjMat) addEdge(i, j int) {
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// Handle index out of bounds and equality
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if i < 0 || j < 0 || i >= g.size() || j >= g.size() || i == j {
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fmt.Errorf("%s", "Index Out Of Bounds Exception")
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}
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// In an undirected graph, the adjacency matrix is symmetric about the main diagonal, i.e., satisfies (i, j) == (j, i)
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g.adjMat[i][j] = 1
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g.adjMat[j][i] = 1
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}
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/* Remove edge */
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// Parameters i, j correspond to vertices element indices
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func (g *graphAdjMat) removeEdge(i, j int) {
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// Handle index out of bounds and equality
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if i < 0 || j < 0 || i >= g.size() || j >= g.size() || i == j {
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fmt.Errorf("%s", "Index Out Of Bounds Exception")
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}
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g.adjMat[i][j] = 0
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g.adjMat[j][i] = 0
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}
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/* Print adjacency matrix */
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func (g *graphAdjMat) print() {
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fmt.Printf("\tVertex list = %v\n", g.vertices)
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fmt.Printf("\tAdjacency matrix = \n")
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for i := range g.adjMat {
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fmt.Printf("\t\t\t%v\n", g.adjMat[i])
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}
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}
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