zoj 2326 Tangled in Cables

#include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
using namespace std;

#define MAXN 1001
#define MAX_PRICE 1<<30
#define names char

double net[MAXN][MAXN];
double minimun[MAXN];
bool used[MAXN];
int n;
double cable;
double sum;
void init()
{
scanf("%lf",&cable);
scanf("%d",&n);
std::map<string, int> name_map;
names houseA[255],houseB[255];
string tmp;
for (int i=1;i<=n;i++){
scanf("%s",&houseA);
tmp = houseA;
name_map[tmp] = i;
used[i] = false;
minimun[i] = MAX_PRICE;
}
int m;
scanf("%d",&m);
int x,y;
for (int i=1;i<=m;i++){
scanf("%s %s",houseA,houseB);
tmp = houseA;
x = name_map[tmp];
tmp = houseB;
y = name_map[tmp];
scanf("%lf",&net[x][y]);
net[y][x] = net[x][y];
}

}
void prim()
{
minimun[1] = 0;
used[1] = true;
sum = 0;
int now = 1;
for (int i=1;i<n;i++){
double min = MAX_PRICE;
int next = 0;
for (int j=1;j<=n;j++){
if (!used[j]){
if(net[now][j]!=0&&minimun[j] > net[now][j]){
minimun[j] = net[now][j];
}
if(min>minimun[j]){
min = minimun[j];
next = j;
}
}
}
sum += min;
now = next;
used[now] = true;
}
if (sum>cable){
printf("Not enough cable\n");
}else {
printf("Need %.1lf miles of cable\n",sum);
}

}

int main()
{
memset(net,0,sizeof(net));
init();
prim();
return 0;
}