Prim演算法實現最小生成樹（鄰接矩陣儲存圖）
程式碼如下
#include <stdio.h>
#include <stdlib.h>
#define MAXSIZE 100
typedef struct
{
int vertex[MAXSIZE];
int edges[MAXSIZE][MAXSIZE];
}Graph;
void creatGraph(Graph *p)
{
int n,e,i,j,k,x;
printf(“print the number of vertex\n”);
scanf("%d",&n);
// printf(“input data of vertex\n”);
for(i=0;i<n;i++)//初始化頂點資訊
{
//scanf("%d",&j);
//p->vertex[i]=j;
p->vertex[i]=i;
}
for(i=0;i<n;i++)//初始化邊關係
for(j=0;j<n;j++)
p->edges[i][j]=9;
printf("print the number of edges\n");
scanf("%d",&e);
for(k=0;k<e;k++)
{
printf("input edge of(i,j)\n");
scanf("%d%d",&i,&j);
printf("input the value of it\n");
scanf("%d",&x);
p->edges[i][j]=x;
p->edges[j][i]=x;
}
}
void showGraph(Graph *p,int n)
{
int i,j;
printf(“vertex\n”);
for(i=0;i<n;i++)
printf("%4d",p->vertex[i]);
for(i=0;i<n;i++)
{
printf("\n");
for(j=0;j<n;j++)
printf("%4d",p->edges[i][j]);
}
}
void Prim(int gm[][MAXSIZE],int n)//gm 鄰接矩陣，n為頂點數，生成的最小生成樹存在closevertex
{
int lowcost[MAXSIZE];
int closevertex[MAXSIZE];
int i,j,k,mincost;
for(i=0;i<n;i++)
{
lowcost[i]=gm[0][i];
closevertex[i]=0;
} lowcost[0]=0; closevertex[0]=0; printf("\n"); for(i=1;i<n;i++)//在n個頂點中生成有n-1條邊的最小生成樹 { mincost=MAXSIZE; j=1;k =0; while(j<n) { if(lowcost[j]!=0&&lowcost[j]<mincost) { mincost=lowcost[j]; k=j; } j++; } printf("Edge:(%d,%d),Wight:%d\n",k,closevertex[k],mincost); lowcost[k]=0; for(j=1;j<n;j++) if(lowcost[j]!=0&&gm[k][j]<lowcost[j]) { lowcost[j]=gm[k][j]; closevertex[j]=k; } } for(int i=0;i<n;i++) printf("%4d",closevertex[i]);
}
int main()
{
Graph M,*p=&M;
creatGraph§;
showGraph(p,6);
Prim(&(p->edges[0]),6);
return 0;
}
測試資料 p184頁
