Prim 算法代码例子

#include <stdio.h>
#include <stdlib.h>
#include <iostream.h>

#define INFINITY INT_MAX
#define MAX_VERTEX_NUM 20

typedef int VRType;
typedef int InfoType;
typedef char VerTexType;

typedef struct ArcCell
{
VRType adj;
InfoType *info;
}ArcCell, AdjMatrix[MAX_VERTEX_NUM][MAX_VERTEX_NUM];

typedef struct
{
VerTexType vexs[MAX_VERTEX_NUM];
AdjMatrix arcs;
int vexnum, arcnum;
}MGraph;

typedef struct
{
VerTexType adjvex;
VRType lowcost;
}closedge[MAX_VERTEX_NUM];

void CreateGraph(MGraph &G);
void MiniSpanTree_PRIM(MGraph G, VerTexType u);
int LocateVex(MGraph G, VerTexType u);
int minimum(closedge close);

void main( void )
{
int i, j;
MGraph G;

CreateGraph(G);
for(i = 0; i < G.vexnum; i++)
{
for(j = 0; j < G.vexnum; j++)
{
cout<<G.arcs[i][j].adj;
cout<<" ";
}
cout<<endl;
}
MiniSpanTree_PRIM(G, 'a');

}
void CreateGraph(MGraph &G)
{
int weigh;
int i, j = 0, k = 0;
char hand, tide;

cout<<"input the number for vexnum and arcnum:";
cin>>G.vexnum>>G.arcnum;

for(i = 0; i < G.vexnum; i++)
{
for(j = 0; j < G.vexnum; j++)
G.arcs[i][j].adj = 88;
}

cout<<endl;
cout<<"input"<<G.vexnum<<"char for vexs:";
for(i=0; i < G.vexnum; i++)
cin>>G.vexs[i];
cout<<endl;
cout<<"input"<<G.arcnum<<"arc(char,char,weigh):"<<endl;
j = 0;
k = 0;
for(i=0; i < G.arcnum; i++)
{
cout<<i<<":";
cin>>hand;
cin>>tide;
cin>>weigh;
while (hand != G.vexs[j])
j++;
while (tide != G.vexs[k])
k++;
G.arcs[j][k].adj = weigh;
G.arcs[k][j].adj = weigh;
j = 0;
k = 0;
cout<<endl;
}
}

void MiniSpanTree_PRIM(MGraph G,VerTexType u)
{
int i, j, k = 0;
closedge close;

k = LocateVex ( G, u );
for ( j = 0; j < G.vexnum; j++ )
{
if (j != k)
{
close[j].adjvex = G.vexs[k];
close[j].lowcost = G.arcs[k][j].adj;
}
}
close[j].lowcost = 88;
close[j].adjvex = '\0';
close[k].lowcost = 0;
close[k].adjvex = u;
for (i = 1; i < G.vexnum; i++)
{
k = minimum(close);
cout<<close[k].adjvex;
cout<<"---->";
cout<<G.vexs[k]<<"";
cout<<close[k].lowcost<<endl;
close[k].lowcost = 0;
for (j=0; j<G.vexnum; j++)
{
if (G.arcs[k][j].adj < close[j].lowcost)
{
close[j].adjvex = G.vexs[k];
close[j].lowcost = G.arcs[k][j].adj;
}
}
}
}

int LocateVex(MGraph G, VerTexType u)
{
int k = 0;

while(G.vexs[k++] == u)
return k-1;
return 0;
}

int minimum(closedge close)
{
int j1=0, client = 88, j2;
while(close[j1].adjvex != '\0')
{
if (client > close[j1].lowcost && close[j1].lowcost != 0)
{
client = close[j1].lowcost;
j2 = j1;
}
j1++;
}
return j2;
}

---

输入输出实例：
input the number for vexnum and arcnum:6 10

input6char for vexs:a
b
c
d
e
f

input10arc(char,char,weigh):
0:a
b
6

1:b
c
5

2:a
c
1

3:a
d
5

4:c
d
5

5:b
e
3

6:c
e
6

7:c
f
4

8:e
f
6

9:d
f
2

88 6 1 5 88 88
6 88 5 88 3 88
1 5 88 5 6 4
5 88 5 88 88 2
88 3 6 88 88 6
88 88 4 2 6 88
a---->c 1
c---->f 4
f---->d 2
c---->b 5
b---->e 3
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