|
| 1 | +# Challenge Description and Solution |
| 2 | + |
| 3 | +## English Version |
| 4 | + |
| 5 | +### Challenge Description |
| 6 | +Implement breadth-first search (BFS) and depth-first search (DFS) algorithms to traverse a graph represented by adjacency lists. Ensure coverage of both connected and disconnected graphs. |
| 7 | + |
| 8 | +### Code Explanation |
| 9 | +The `Graph` class represents an undirected graph using adjacency lists. It supports: |
| 10 | +- `addEdge(u, v)`: Adds an undirected edge between vertices `u` and `v`. |
| 11 | +- `bfs(start)`: Performs BFS traversal starting from a given vertex. |
| 12 | +- `dfs(start)`: Performs DFS traversal starting from a given vertex. |
| 13 | +- `bfsDisconnected()`: Performs BFS traversal covering all vertices, including disconnected components. |
| 14 | +- `dfsDisconnected()`: Performs DFS traversal covering all vertices, including disconnected components. |
| 15 | + |
| 16 | +### Relevant Code Snippet |
| 17 | + |
| 18 | +```javascript |
| 19 | +class Graph { |
| 20 | + constructor(vertices) { |
| 21 | + this.V = vertices; |
| 22 | + this.adj = Array.from({ length: vertices }, () => []); |
| 23 | + } |
| 24 | + |
| 25 | + addEdge(u, v) { |
| 26 | + this.adj[u].push(v); |
| 27 | + this.adj[v].push(u); // Undirected graph |
| 28 | + } |
| 29 | + |
| 30 | + bfs(start) { |
| 31 | + const visited = new Array(this.V).fill(false); |
| 32 | + const queue = []; |
| 33 | + const result = []; |
| 34 | + |
| 35 | + visited[start] = true; |
| 36 | + queue.push(start); |
| 37 | + |
| 38 | + while (queue.length > 0) { |
| 39 | + const vertex = queue.shift(); |
| 40 | + result.push(vertex); |
| 41 | + |
| 42 | + for (const neighbor of this.adj[vertex]) { |
| 43 | + if (!visited[neighbor]) { |
| 44 | + visited[neighbor] = true; |
| 45 | + queue.push(neighbor); |
| 46 | + } |
| 47 | + } |
| 48 | + } |
| 49 | + return result; |
| 50 | + } |
| 51 | + |
| 52 | + dfsUtil(v, visited, result) { |
| 53 | + visited[v] = true; |
| 54 | + result.push(v); |
| 55 | + |
| 56 | + for (const neighbor of this.adj[v]) { |
| 57 | + if (!visited[neighbor]) { |
| 58 | + this.dfsUtil(neighbor, visited, result); |
| 59 | + } |
| 60 | + } |
| 61 | + } |
| 62 | + |
| 63 | + dfs(start) { |
| 64 | + const visited = new Array(this.V).fill(false); |
| 65 | + const result = []; |
| 66 | + this.dfsUtil(start, visited, result); |
| 67 | + return result; |
| 68 | + } |
| 69 | + |
| 70 | + bfsDisconnected() { |
| 71 | + const visited = new Array(this.V).fill(false); |
| 72 | + const result = []; |
| 73 | + |
| 74 | + for (let i = 0; i < this.V; i++) { |
| 75 | + if (!visited[i]) { |
| 76 | + const queue = []; |
| 77 | + visited[i] = true; |
| 78 | + queue.push(i); |
| 79 | + |
| 80 | + while (queue.length > 0) { |
| 81 | + const vertex = queue.shift(); |
| 82 | + result.push(vertex); |
| 83 | + |
| 84 | + for (const neighbor of this.adj[vertex]) { |
| 85 | + if (!visited[neighbor]) { |
| 86 | + visited[neighbor] = true; |
| 87 | + queue.push(neighbor); |
| 88 | + } |
| 89 | + } |
| 90 | + } |
| 91 | + } |
| 92 | + } |
| 93 | + return result; |
| 94 | + } |
| 95 | + |
| 96 | + dfsDisconnected() { |
| 97 | + const visited = new Array(this.V).fill(false); |
| 98 | + const result = []; |
| 99 | + |
| 100 | + for (let i = 0; i < this.V; i++) { |
| 101 | + if (!visited[i]) { |
| 102 | + this.dfsUtil(i, visited, result); |
| 103 | + } |
| 104 | + } |
| 105 | + return result; |
| 106 | + } |
| 107 | +} |
| 108 | +``` |
| 109 | + |
| 110 | +### Example Usage |
| 111 | + |
| 112 | +```javascript |
| 113 | +import Graph from './graph.js'; |
| 114 | + |
| 115 | +const g = new Graph(7); |
| 116 | +const edges = [[0, 1], [0, 2], [1, 3], [1, 4], [2, 5], [5, 6]]; |
| 117 | +for (const [u, v] of edges) { |
| 118 | + g.addEdge(u, v); |
| 119 | +} |
| 120 | + |
| 121 | +console.log('BFS starting from vertex 0:'); |
| 122 | +console.log(g.bfs(0)); |
| 123 | + |
| 124 | +console.log('DFS starting from vertex 0:'); |
| 125 | +console.log(g.dfs(0)); |
| 126 | + |
| 127 | +console.log('BFS for disconnected graph:'); |
| 128 | +console.log(g.bfsDisconnected()); |
| 129 | + |
| 130 | +console.log('DFS for disconnected graph:'); |
| 131 | +console.log(g.dfsDisconnected()); |
| 132 | +``` |
| 133 | + |
| 134 | +--- |
| 135 | + |
| 136 | +## Versión en Español |
| 137 | + |
| 138 | +### Descripción del Reto |
| 139 | +Implementa los algoritmos de búsqueda en anchura (BFS) y búsqueda en profundidad (DFS) para recorrer un grafo representado por listas de adyacencia. Asegura la cobertura de grafos conectados y desconectados. |
| 140 | + |
| 141 | +### Explicación del Código |
| 142 | +La clase `Graph` representa un grafo no dirigido usando listas de adyacencia. Soporta: |
| 143 | +- `addEdge(u, v)`: Añade una arista no dirigida entre los vértices `u` y `v`. |
| 144 | +- `bfs(start)`: Realiza un recorrido BFS comenzando desde un vértice dado. |
| 145 | +- `dfs(start)`: Realiza un recorrido DFS comenzando desde un vértice dado. |
| 146 | +- `bfsDisconnected()`: Realiza un recorrido BFS cubriendo todos los vértices, incluyendo componentes desconectados. |
| 147 | +- `dfsDisconnected()`: Realiza un recorrido DFS cubriendo todos los vértices, incluyendo componentes desconectados. |
| 148 | + |
| 149 | +### Fragmento de Código Relevante |
| 150 | + |
| 151 | +```javascript |
| 152 | +class Graph { |
| 153 | + constructor(vertices) { |
| 154 | + this.V = vertices; |
| 155 | + this.adj = Array.from({ length: vertices }, () => []); |
| 156 | + } |
| 157 | + |
| 158 | + addEdge(u, v) { |
| 159 | + this.adj[u].push(v); |
| 160 | + this.adj[v].push(u); // Grafo no dirigido |
| 161 | + } |
| 162 | + |
| 163 | + bfs(start) { |
| 164 | + const visited = new Array(this.V).fill(false); |
| 165 | + const queue = []; |
| 166 | + const result = []; |
| 167 | + |
| 168 | + visited[start] = true; |
| 169 | + queue.push(start); |
| 170 | + |
| 171 | + while (queue.length > 0) { |
| 172 | + const vertex = queue.shift(); |
| 173 | + result.push(vertex); |
| 174 | + |
| 175 | + for (const neighbor of this.adj[vertex]) { |
| 176 | + if (!visited[neighbor]) { |
| 177 | + visited[neighbor] = true; |
| 178 | + queue.push(neighbor); |
| 179 | + } |
| 180 | + } |
| 181 | + } |
| 182 | + return result; |
| 183 | + } |
| 184 | + |
| 185 | + dfsUtil(v, visited, result) { |
| 186 | + visited[v] = true; |
| 187 | + result.push(v); |
| 188 | + |
| 189 | + for (const neighbor of this.adj[v]) { |
| 190 | + if (!visited[neighbor]) { |
| 191 | + this.dfsUtil(neighbor, visited, result); |
| 192 | + } |
| 193 | + } |
| 194 | + } |
| 195 | + |
| 196 | + dfs(start) { |
| 197 | + const visited = new Array(this.V).fill(false); |
| 198 | + const result = []; |
| 199 | + this.dfsUtil(start, visited, result); |
| 200 | + return result; |
| 201 | + } |
| 202 | + |
| 203 | + bfsDisconnected() { |
| 204 | + const visited = new Array(this.V).fill(false); |
| 205 | + const result = []; |
| 206 | + |
| 207 | + for (let i = 0; i < this.V; i++) { |
| 208 | + if (!visited[i]) { |
| 209 | + const queue = []; |
| 210 | + visited[i] = true; |
| 211 | + queue.push(i); |
| 212 | + |
| 213 | + while (queue.length > 0) { |
| 214 | + const vertex = queue.shift(); |
| 215 | + result.push(vertex); |
| 216 | + |
| 217 | + for (const neighbor of this.adj[vertex]) { |
| 218 | + if (!visited[neighbor]) { |
| 219 | + visited[neighbor] = true; |
| 220 | + queue.push(neighbor); |
| 221 | + } |
| 222 | + } |
| 223 | + } |
| 224 | + } |
| 225 | + } |
| 226 | + return result; |
| 227 | + } |
| 228 | + |
| 229 | + dfsDisconnected() { |
| 230 | + const visited = new Array(this.V).fill(false); |
| 231 | + const result = []; |
| 232 | + |
| 233 | + for (let i = 0; i < this.V; i++) { |
| 234 | + if (!visited[i]) { |
| 235 | + this.dfsUtil(i, visited, result); |
| 236 | + } |
| 237 | + } |
| 238 | + return result; |
| 239 | + } |
| 240 | +} |
| 241 | +``` |
| 242 | + |
| 243 | +### Ejemplo de Uso |
| 244 | + |
| 245 | +```javascript |
| 246 | +import Graph from './graph.js'; |
| 247 | + |
| 248 | +const g = new Graph(7); |
| 249 | +const edges = [[0, 1], [0, 2], [1, 3], [1, 4], [2, 5], [5, 6]]; |
| 250 | +for (const [u, v] of edges) { |
| 251 | + g.addEdge(u, v); |
| 252 | +} |
| 253 | + |
| 254 | +console.log('BFS starting from vertex 0:'); |
| 255 | +console.log(g.bfs(0)); |
| 256 | + |
| 257 | +console.log('DFS starting from vertex 0:'); |
| 258 | +console.log(g.dfs(0)); |
| 259 | + |
| 260 | +console.log('BFS for disconnected graph:'); |
| 261 | +console.log(g.bfsDisconnected()); |
| 262 | + |
| 263 | +console.log('DFS for disconnected graph:'); |
| 264 | +console.log(g.dfsDisconnected()); |
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