单源无权最短路径 C实现~

利用广度优先搜索实现（BFS应用）

文件头:

#include<stdio.h>#include<stdlib.h>#include<ctype.h>#define INFINITY 65535#define NOTEXIST -1#define MAXVEX 100int path[MAXVEX];int dist[MAXVEX];typedef char VertexType;typedef struct QNode {int front, rear;int data[MAXVEX];int size;}Queue;typedef struct ENode {int ivex;//顶点 索引  struct ENode* next_edge;}ENode;typedef struct VNode {VertexType data; // 顶点 信息  ENode* first_edge;}VNode;typedef struct Graph {VNode vex[MAXVEX];int vex_num, edge_num;}Graph;

核心代码：

void unweight_path(Graph g, int start){Queue q;init_queue(&q);enqueue(start, &q);int v;while (!is_empty(q)) {v = get_front(q);dequeue(&q);ENode* p;p = g.vex[v].first_edge;while (p != NULL) {if (dist[p->ivex] == INFINITY) {dist[p->ivex] = dist[v] + 1;path[p->ivex] = v;enqueue(p->ivex, &q);}p = p->next_edge;}}}

补充一种打印最短路径方法:(类似后续遍历)

void print_path2(Graph g, int index)//这里 直接传递最后位置的索引 {if (path[index] != NOTEXIST) {print_path2(g, path[index]);printf("->");}printf("%c", g.vex[index].data);}

完整代码实现：

#include<stdio.h>#include<stdlib.h>#include<ctype.h>#define INFINITY 65535#define NOTEXIST -1#define MAXVEX 100int path[MAXVEX];int dist[MAXVEX];typedef char VertexType;typedef struct QNode {int front, rear;int data[MAXVEX];int size;}Queue;typedef struct ENode {int ivex;//顶点 索引  struct ENode* next_edge;}ENode;typedef struct VNode {VertexType data; // 顶点 信息  ENode* first_edge;}VNode;typedef struct Graph {VNode vex[MAXVEX];int vex_num, edge_num;}Graph;int init_queue(Queue *q){//q = (Queue*)malloc(sizeof(Queue));// 不能加这个 切记  q->size = 0;q->rear = 0;q->front = 0;return 1;}int is_full(Queue q){return (q.rear + 1) % MAXVEX == q.front;}int is_empty(Queue q){return q.front == q.rear;}void enqueue(int x, Queue *q){if (!is_full(*q)) {q->data[q->rear] = x;q->rear = (q->rear + 1) % MAXVEX;q->size++;}}void dequeue(Queue *q){if (!is_empty(*q)) {q->front = (q->front + 1) % MAXVEX;q->size--;}}int get_front(Queue q){if (!is_empty(q)) {return q.data[q.front];}}char read_char(){char ch;do {ch = getchar();} while (!isalpha(ch));return ch;}int get_pos(Graph g, char ch){int i;for (i = 0; i < g.vex_num; i++) {if (ch == g.vex[i].data)return i;}return -1;}void link_last(ENode* list, ENode *last){ENode* p;p = list;while (p->next_edge != NULL) {p = p->next_edge;}p->next_edge = last;}void create_graph(Graph *g){int i;printf("请输入顶点数和边数:\n");scanf("%d%d", &g->vex_num, &g->edge_num);printf("请输入顶点信息:\n");for (i = 0; i < g->vex_num; i++) {g->vex[i].first_edge = NULL;g->vex[i].data = read_char();}printf("请输入边 :\n");for (i = 0; i < g->edge_num; i++) {int p1, p2;char c1, c2;c1 = read_char();c2 = read_char();p1 = get_pos(*g, c1);p2 = get_pos(*g, c2);ENode* node1;node1 = (ENode*)malloc(sizeof(ENode));if (node1 == NULL) {printf("error");return;}node1->next_edge = NULL;node1->ivex = p2;if (g->vex[p1].first_edge == NULL)g->vex[p1].first_edge = node1;elselink_last(g->vex[p1].first_edge, node1);}}void print_graph(Graph g){int i;ENode* p;for (i = 0; i < g.vex_num; i++) {printf("%c", g.vex[i].data);p = g.vex[i].first_edge;while (p != NULL) {printf("(%c, %c)", g.vex[i].data, g.vex[p->ivex].data);p = p->next_edge;}printf("\n");}}void init_graph(Graph g, int start){int i;for (i = 0; i < g.vex_num; i++) {dist[i] = INFINITY;path[i] = NOTEXIST;}dist[start] = 0;}void unweight_path(Graph g, int start){Queue q;init_queue(&q);enqueue(start, &q);int v;while (!is_empty(q)) {v = get_front(q);dequeue(&q);ENode* p;p = g.vex[v].first_edge;while (p != NULL) {if (dist[p->ivex] == INFINITY) {dist[p->ivex] = dist[v] + 1;path[p->ivex] = v;enqueue(p->ivex, &q);}p = p->next_edge;}}}int print_path(Graph g, int end){int pos, i;pos = end;i = pos;int cnt = 1;// 记录该最短路径有几个元素 int count;for (; path[i] != NOTEXIST; i = path[i]) {cnt++;}count = cnt;char* ins = (char*)malloc(sizeof(char)*cnt);if (cnt == 1) {printf("不存在该路径");return 0;}ins[0] = g.vex[i].data;//路径初始位置 i = pos;//把 路径 反序记入 数组 for (; path[i] != NOTEXIST; i = path[i]) {ins[--cnt] = g.vex[i].data;}//打印 该路径  int flag = 1;for (i = 0; i < count; i++) {if (flag == 1) {flag = 0;printf("%c", ins[i]);}else {printf("->%c", ins[i]);}}}void print_path2(Graph g, int index)//这里 直接传递最后位置的索引 {if (path[index] != NOTEXIST) {print_path2(g, path[index]);printf("->");}printf("%c", g.vex[index].data);}int main(){Graph g;int start, end;char ch1, ch2;create_graph(&g);printf("请输入起始点与终点:\n");ch1 = read_char();ch2 = read_char();start = get_pos(g, ch1);end = get_pos(g, ch2);init_graph(g, start);unweight_path(g, start);end = get_pos(g, ch2);print_path(g, end);//print_path2(g, end);//print_graph(g);getchar();getchar();return 0;}