给定如下C++实现的邻接表版Dijkstra算法程序,假设图graph的顶点数为v、边数为e,求该程序的时间复杂度:
typedef struct Edge {
int in, out; // 从下标in顶点到下标out顶点的边
int len; // 边长度
struct Edge * next;
} Edge;
// v: 顶点个数,graph: 出边邻接表,start: 起点下标,dis: 输出每个顶点的最短距离
void dijkstra(int v, Edge * graph[], int start, int * dis) {
const int MAX_DIS = 0x7fffff;
for (int i = 0; i < v; i++)
dis[i] = MAX_DIS;
dis[start] = 0;
int * visited = new int[v];
for (int i = 0; i < v; i++)
visited[i] = 0;
visited[start] = 1;
for (int t = 0;; t++) {
int min = MAX_DIS, minv = -1;
for (int i = 0; i < v; i++) {
if (visited[i] == 0 && min > dis[i]) {
min = dis[i];
minv = i;
}
}
if (minv < 0)
break;
visited[minv] = 1;
for (Edge * e = graph[minv]; e != NULL; e = e->next)
if (dis[e->out] > e->len)
dis[e->out] = e->len;
}
delete[] visited;
}