08-图7 公路村村通 (30 分)

/*prim算法*/
  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #define MAX 1002
  4 #define INF 500001
  5 
  6 typedef int Vertex;
  7 typedef int Weight;
  8 
  9 typedef struct ENode* Edge;
 10 struct ENode {
 11     Vertex V1;
 12     Vertex V2;
 13     Weight W;
 14 };
 15 
 16 typedef struct GNode* MGraph;
 17 struct GNode {
 18     int N;
 19     int M;
 20     Vertex G[MAX][MAX];
 21 };
 22 MGraph CreateGraph();
 23 MGraph BuildGraph();
 24 void InsertVertex(MGraph Graph, Edge E);
 25 void Prim(MGraph Graph, Vertex dist[], Vertex parent[]);
 26 
 27 int main()
 28 {
 29     MGraph Graph;
 30     Vertex dist[MAX], parent[MAX];
 31     for (int i = 0; i < MAX; i++)
 32     {
 33         dist[i] = INF;
 34         parent[i] = 0;
 35     }
 36     Graph = BuildGraph();
 37     Prim(Graph, dist, parent);
 38 }
 39 
 40 MGraph CreateGraph()
 41 {
 42     MGraph Graph = (MGraph)malloc(sizeof(struct GNode));
 43     scanf("%d%d", &Graph->N, &Graph->M);
 44     for (int i = 0; i < Graph->N; i++)
 45         for (int j = 0; j < MAX; j++)
 46             Graph->G[i][j] = Graph->G[j][i] = INF;
 47     return Graph;
 48 }
 49 
 50 MGraph BuildGraph()
 51 {
 52     MGraph G;
 53     Edge E = NULL;
 54     E = (Edge)malloc(sizeof(struct ENode));
 55     G = CreateGraph();
 56     int i;
 57     for (i = 0; i < G->M; i++)
 58     {
 59         scanf("%d%d%d", &E->V1, &E->V2, &E->W);
 60         InsertVertex(G, E);
 61     }
 62     return G;
 63 }
 64 
 65 void InsertVertex(MGraph Graph, Edge E)
 66 {
 67     Graph->G[E->V1][E->V2] = Graph->G[E->V2][E->V1] = E->W;
 68 }
 69 
 70 int FindMinDist(MGraph Graph, Vertex dist[],Vertex parent[]) {
 71     int v, MinDist = INF, Minv = 0;
 72     for (v = 0; v <= Graph->N; v++)
 73     {
 74         if (dist[v]!=0 && dist[v] < MinDist) {
 75             MinDist = dist[v];
 76             Minv = v;
 77         }
 78     }
 79     if (MinDist == INF||Minv==0) return 0;
 80     return Minv;
 81 }
 82 
 83 void Prim(MGraph Graph, Vertex dist[], Vertex parent[])
 84 {
 85     int i, MST=0, V,cost=0;
 86     for (i = 0; i <= Graph->N; i++)
 87     {
 88         if (Graph->G[1][i] != INF) parent[i] = 1;
 89         else parent[i] = -1;
 90         dist[i] = Graph->G[1][i];
 91     }
 92     dist[1] = 0;
 93     while (1) {
 94         V = FindMinDist(Graph, dist,parent);
 95         if (V == 0) break;
 96         cost += dist[V];
 97         dist[V] = 0;MST++;
 98         for (i = 0; i < Graph->N; i++)
 99             if (dist[i] != 0)
100                 if (Graph->G[V][i] < dist[i])
101                 {
102                     dist[i] = Graph->G[V][i];
103                     parent[i] = V;
104                 }
105     }
106     if (MST == Graph->N-1) printf("%d", cost);
107     else printf("-1\n");
108 }