C++ :

//求某些点已经被连接的 最小生成树
#include <stack>
#include <set>
#include <vector>
#include <math.h>
#include <string.h>
#include <algorithm>
using namespace std;
#define N 102
int map[N][N];
bool b[N];
int n;
int Prim()
{
    int i,sum=0,k;
    int t=n;
    int Min;
    memset(b,0,sizeof(b));
    while(--t)
    {
        Min=10000;
        for(i=2;i<=n;i++)
         if(!b[i]&&Min>map[1][i])
          {
              Min=map[1][i];
              k=i;
          }
       //   printf("%d ",Min);
          b[k]=1;
          sum+=Min;
          for(i=2;i<=n;i++)
           if(!b[i]&&map[k][i]<map[1][i])
             map[1][i]=map[k][i];
    }
    return sum;
}
int main()
{
  //  freopen("roads.in", "r", stdin);
  //  freopen("roads.out", "w", stdout);
    int i,j,q;
    while(scanf("%d",&n)!=EOF)
    {
        for(i=1;i<=n;i++)
         for(j=1;j<=n;j++)
          scanf("%d",&map[i][j]);
        scanf("%d",&q);
        while(q--)
        {
            scanf("%d %d",&i,&j);
            map[i][j]=0;
            map[j][i]=0;
        }
        printf("%d\n",Prim());
    }
    return 0;
}

Pascal :

var ans,n,min,i,j,q,p,x,y:longint;
a:array[0..101,0..101] of longint;
d,f:array[0..101] of longint;
v:array[0..101] of boolean;

procedure prim;
var i,j:longint;
begin
  for i:=1 to n do d[i]:=maxlongint;
  d[1]:=0;
  for i:=1 to n do f[i]:=1;
  for i:=1 to n do
  begin
    min:=maxlongint;
    for j:=1 to n do
      if (v[j]=false) and (d[j]<min) then
        begin
          min:=d[j];
          q:=j;
        end;
    ans:=ans+a[q,f[q]];
    v[q]:=true;
    for j:=1 to n do
      if (q<>j) and (v[j]=false) and (a[q,j]>=0) and (a[q,j]<d[j]) then
        begin
          d[j]:=a[q,j];
          f[j]:=q;
        end;
  end;
end;

begin
readln(n);
for i:=1 to n do
for j:=1 to n do
read(a[i,j]);
readln(p);
for i:=1 to p do
begin
  read(x,y);
  a[x,y]:=0;
  a[y,x]:=0;
end;
prim;
write(ans);
end.
AC