java实现DFS,BFS算法
源代码
图的结构java实现
public class DFSAndBFS {
/**
* BFS 只能遍历连通图
*
* @param graph 图
* @param i 起始访问下标
* @param flag 访问标记数组
* @param queue 访问队列
*/
private static void BFS(GraphMatrix graph, int i, boolean[] flag, Queue<Integer> queue) {
if (!flag[i]) {
flag[i] = true;
System.out.print(graph.vertexList.get(i) + " ");
queue.offer(i);
while (!queue.isEmpty()) {
//取出队列中结点
int k = queue.poll();
for (int j = 0; j < graph.getVertexNum(); j++) {
//访问与k结点相连的所有结点，如果没有被访问，标记结点
if (graph.edges[k][j] == 1 && !flag[j]) {
flag[j] = true;
System.out.print(graph.vertexList.get(j) + " ");
//结点插入队列
queue.offer(j);
}
}
}
}
}
/**
* BFS 可以遍历非连通图
*
* @param graph 图
*/
static void BFSTraverse(GraphMatrix graph) {
boolean[] flag = new boolean[graph.getVertexNum()];
Queue<Integer> queue = new LinkedList<>();
for (int i = 0; i < graph.getVertexNum(); i++) {
BFS(graph, i, flag, queue);
}
}
/**
* DFS 只能遍历连通图
*
* @param graph 图
* @param i 起始访问下标
* @param flag 访问标记数组
*/
private static void DFS(GraphMatrix graph, int i, boolean[] flag) {
flag[i] = true;// 第i个顶点被访问
System.out.print(graph.vertexList.get(i) + " ");
for (int j = 0; j < graph.getVertexNum(); j++) {
if (!flag[j] && graph.edges[i][j] == 1) {
DFS(graph, j, flag);
}
}
}
static void DFSTraverse(GraphMatrix graph) {
boolean[] flag = new boolean[graph.getVertexNum()];
for (int i = 0; i < graph.getVertexNum(); i++) {
if (!flag[i]) {// 当前顶点没有被访问
DFS(graph, i, flag);
}
}
}
/**
* DFS非递归
*
* @param graph
*/
static void DFS_Map(GraphMatrix graph) {
boolean[] flag = new boolean[graph.getVertexNum()];
LinkedList<Integer> stack = new LinkedList<>();
for (int i = 0; i < graph.getVertexNum(); i++) {
if (!flag[i]) {
flag[i] = true;
System.out.print(graph.vertexList.get(i) + " ");
stack.push(i);
}
while (!stack.isEmpty()) {
int k = stack.pop();
for (int j = 0; j < graph.getVertexNum(); j++) {
if (graph.edges[k][j] == 1 && !flag[j]) {
flag[j] = true;
System.out.print(graph.vertexList.get(j) + " ");
stack.push(j);
break;
}
}
}
}
}
public static void main(String[] args) {
GraphMatrix<String> graph = new GraphMatrix<>("ABCDEFGHI");
graph.addEdge("A", "B");
graph.addEdge("A", "F");
graph.addEdge("A", "G");
graph.addEdge("B", "C");
graph.addEdge("B", "G");
graph.addEdge("B", "I");
graph.addEdge("C", "D");
graph.addEdge("C", "I");
graph.addEdge("D", "E");
graph.addEdge("D", "G");
graph.addEdge("D", "H");
graph.addEdge("D", "I");
graph.addEdge("E", "F");
graph.addEdge("E", "H");
graph.addEdge("F", "G");
graph.addEdge("G", "H");
graph.information();
System.out.println("DFS递归:");
DFSTraverse(graph);
System.out.println("\nDFS非递归:");
DFS_Map(graph);
System.out.println("\nBFS非递归:");
BFSTraverse(graph);
}
}log
边的权重表:
0 1 0 0 0 1 1 0 0
1 0 1 0 0 0 1 0 1
0 1 0 1 0 0 0 0 1
0 0 1 0 1 0 1 1 1
0 0 0 1 0 1 0 1 0
1 0 0 0 1 0 1 0 0
1 1 0 1 0 1 0 1 0
0 0 0 1 1 0 1 0 0
0 1 1 1 0 0 0 0 0
DFS递归:
A B C D E F G H I
DFS非递归:
A B C D E F G H I
BFS非递归:
A B F G C I E D H
