1 int BFS ( Vertex V )
 2 { 
 3 visited[V] = true; count = 1;
 4 level = 0; last = V;
 5 Enqueue(V, Q);
 6 while(!IsEmpty(Q)){ 
 7 V = Dequeue(Q);
 8 for( V 的每个邻接点 W )
 9 if( !visited[W] ) {
10 visited[W] = true;
11 Enqueue(W, Q); count++;
12 tail = W;
13 }
14 if( V == last ) {
15 level++; last = tail;
16 }
17 if( level == 6) break;
18 }
19 Reset(V) // 重置V的每个邻接点访问状态
20 returncount;
21 }

1 void SDS() {
2 for V in G {
3 count = BFS(V)
4 print(count)
5 }  
6 }

  1 #pragma mark - 六度空间
  2 #include <math.h>
  3 #include <stdio.h>
  4 #include <stdbool.h>
  5 typedef struct {
  6 int index;
  7 bool visited;
  8 void *next;
  9 } SDSVertex;
 10 int a[10000][10000];
 11 SDSVertex v_sds[10000];
 12 int pNum = 0, edgeNum = 0;
 13 typedef struct queue {
 14 SDSVertex *front;
 15 SDSVertex *rear;
 16 } Queue;
 17 Queue *createQueue()
 18 Queue *queue = (Queue *)malloc(sizeof(Queue));
 19 queue->front = NULL;
 20 queue->rear = NULL;
 21 return queue;
 22 }
 23 void addToQueue(Queue *queue, SDSVertex *node)
 24 {
 25 if (!(queue->rear)) {
 26 queue->rear = node;
 27 } else {
 28 queue->rear->next = node;
 29 queue->rear = node;
 30 }
 31 if (!(queue->front)) {
 32 queue->front = node;
 33 }
 34 }
 35 SDSVertex *deleteFromQueue(Queue *queue)
 36 {
 37 SDSVertex *temp = queue->front;
 38 if (temp) {
 39 queue->front = queue->front->next;
 40 return temp;
 41 } else {
 42 return NULL;
 43 }
 44 }
 45 int isEmptyQueue(Queue *queue)
 46 {
 47 if (queue->front == NULL) {
 48 return 1;
 49 } else {
 50 return 0;
 51 }
 52 }
 53 int BFS_SDS(int i)
 54 {
 55 SDSVertex *v = &v_sds[i];
 56 v->visited = true;
 57 int level = 0, count = 1;
 58 SDSVertex *last = v, *tail = NULL;
 59 Queue *queue = createQueue();
 60 addToQueue(queue, v);
 61 while (!isEmptyQueue(queue)) {
 62 SDSVertex *vertex = deleteFromQueue(queue);
 63 for (int j = 1; j <= pNum; j++) {
 64 int hasEdge = a[vertex->index][j];
 65 if (hasEdge && !v_sds[j].visited) {
 66 v_sds[j].visited = true;
 67 addToQueue(queue, &v_sds[j]); count++;
 68 tail = &v_sds[j];
 69 }
 70 }
 71 if (vertex == last) {
 72 level++; last = tail;
 73 }
 74 if (level == 6) {
 75 break;
 76 }
 77 }
 78 for (int i = 1; i <= pNum; i++) {
 79 v_sds[i].visited = false;
 80 v_sds[i].next = NULL;
 81 }
 82 return count;
 83 }
 84 int main()
 85 {
 86 scanf("%d %d", &pNum, &edgeNum);
 87 for (int i = 1; i <= edgeNum; i++) {
 88 int from = 0, to = 0;
 89 scanf("%d %d", &from, &to);
 90 a[from][to] = 1;
 91 a[to][from] = 1;
 92 }
 93 for (int i = 1; i <= pNum; i++) {
 94 v_sds[i].visited = false;
 95 v_sds[i].index = i;
 96 v_sds[i].next = NULL;
 97 }
 98 int count = -1;
 99 for (int i = 1; i <= pNum; i++) {
100 count = BFS_SDS(i);
101 printf("%d: %.2f%%\n", i, count * 100.0 / pNum);
102 }
103 }