poj 1251 && hdu 1301
Sample Input
9 //n 结点数
A 2 B 12 I 25
B 3 C 10 H 40 I 8
C 2 D 18 G 55
D 1 E 44
E 2 F 60 G 38
F 0
G 1 H 35
H 1 I 35
3
A 2 B 10 C 40
B 1 C 20
0
Sample Output
216
30
prim算法
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; const int INF=0x3f3f3f3f;
const int MAXN=;
bool vis[MAXN];
int lowc[MAXN];
int n ;
int cost[MAXN][MAXN] ; int Prim()//点是0~n-1
{
int ans=;
memset(vis,false,sizeof(vis));
vis[]=true;
for(int i=;i<n;i++)lowc[i]=cost[][i];
for(int i=;i<n;i++)
{
int minc=INF;
int p=-;
for(int j=;j<n;j++)
if(!vis[j]&&minc>lowc[j])
{
minc=lowc[j];
p=j;
}
if(minc==INF)return -;//原图不连通
ans+=minc;
vis[p]=true;
for(int j=;j<n;j++)
if(!vis[j]&&lowc[j]>cost[p][j])
lowc[j]=cost[p][j];
}
return ans;
} int main()
{ // freopen("in.txt","r",stdin) ;
while(cin>>n)
{
if (n == )
break ;
char u , v;
int w , num ;
int i , j ;
for (i = ; i < n ; i++)
for (j = ; j < n ; j++)
cost[i][j] = INF ; for (i = ; i < n ; i++)
{
cin>>u>>num ;
while (num--)
{
cin>>v>>w ;
cost[u -'A'][v - 'A'] = w ;
cost[v - 'A'][u -'A'] = w ;
}
}
cout<<Prim()<<endl ; }
return ;
}
Kruskal算法
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; int n ;
const int MAXN=;//最大点数
const int MAXM=;//最大边数
int F[MAXN];//并查集使用
struct Edge
{
int u,v,w;
}edge[MAXM];//存储边的信息，包括起点/终点/权值 int tol;//边数，加边前赋值为0
void addedge(int u,int v,int w)
{ edge[tol].u=u;
edge[tol].v=v;
edge[tol++].w=w;
}
bool cmp(Edge a,Edge b)
{//排序函数，讲边按照权值从小到大排序
return a.w<b.w;
}
int find(int x)
{
if(F[x]==-)return x;
else return F[x]=find(F[x]);
}
int Kruskal()//传入点数，返回最小生成树的权值，如果不连通返回-1
{
memset(F,-,sizeof(F));
sort(edge,edge+tol,cmp);
int cnt=;//计算加入的边数
int ans=;
for(int i=;i<tol;i++)
{
int u=edge[i].u;
int v=edge[i].v;
int w=edge[i].w;
int t1=find(u);
int t2=find(v);
if(t1!=t2)
{
ans+=w;
F[t1]=t2;
cnt++;
}
if(cnt==n-)break;
}
if(cnt<n-)return -;//不连通
else return ans;
} int main()
{ // freopen("in.txt","r",stdin) ;
while(cin>>n)
{
if (n == )
break ;
char u , v;
int w , num ;
int i , j ;
tol = ;
for (i = ; i < n ; i++)
{
cin>>u>>num ;
while (num--)
{
cin>>v>>w ;
addedge(u,v,w) ;
}
}
cout<<Kruskal()<<endl ; }
return ;
}
poj 1258
Sample Input
4 //n
0 4 9 21 //邻接矩阵
4 0 8 17
9 8 0 16
21 17 16 0
Sample Output
28
prim
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; const int INF=0x3f3f3f3f;
const int MAXN=;
bool vis[MAXN];
int lowc[MAXN];
int n ;
int cost[MAXN][MAXN] ; int Prim()//点是0~n-1
{
int ans=;
memset(vis,false,sizeof(vis));
vis[]=true;
for(int i=;i<n;i++)lowc[i]=cost[][i];
for(int i=;i<n;i++)
{
int minc=INF;
int p=-;
for(int j=;j<n;j++)
if(!vis[j]&&minc>lowc[j])
{
minc=lowc[j];
p=j;
}
if(minc==INF)return -;//原图不连通
ans+=minc;
vis[p]=true;
for(int j=;j<n;j++)
if(!vis[j]&&lowc[j]>cost[p][j])
lowc[j]=cost[p][j];
}
return ans;
} int main()
{ //freopen("in.txt","r",stdin) ;
while(cin>>n)
{
int w ;
int i , j ;
for (i = ; i < n ; i++)
for (j = ; j < n ; j++)
{
cin>>w ;
if(w==)
cost[i][j] = INF ;
else
cost[i][j] = w ;
}
cout<<Prim()<<endl ; }
return ;
}
hdu 1863
Sample Input
3 3 //边数 结点数
1 2 1 //一条边两边结点的id 边的权值
1 3 2
2 3 4
1 3
2 3 2
0 100
Sample Output
3
? //不连通就输出这个
Kruskal
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; int n ;
const int MAXN=;//最大点数
const int MAXM=;//最大边数
int F[MAXN];//并查集使用
struct Edge
{
int u,v,w;
}edge[MAXM];//存储边的信息，包括起点/终点/权值 int tol;//边数，加边前赋值为0
void addedge(int u,int v,int w)
{ edge[tol].u=u;
edge[tol].v=v;
edge[tol++].w=w;
}
bool cmp(Edge a,Edge b)
{//排序函数，讲边按照权值从小到大排序
return a.w<b.w;
}
int find(int x)
{
if(F[x]==-)return x;
else return F[x]=find(F[x]);
}
int Kruskal()//传入点数，返回最小生成树的权值，如果不连通返回-1
{
memset(F,-,sizeof(F));
sort(edge,edge+tol,cmp);
int cnt=;//计算加入的边数
int ans=;
for(int i=;i<tol;i++)
{
int u=edge[i].u;
int v=edge[i].v;
int w=edge[i].w;
int t1=find(u);
int t2=find(v);
if(t1!=t2)
{
ans+=w;
F[t1]=t2;
cnt++;
}
if(cnt==n-)break;
}
if(cnt<n-)return -;//不连通
else return ans;
} int main()
{ // freopen("in.txt","r",stdin) ;
int m ;
while(scanf("%d %d" , &m , &n) != EOF)
{
if (m == )
break ;
int i ;
int u , v , w ;
tol = ;
while(m--)
{
scanf("%d %d %d" , &u , &v , &w) ;
addedge(u , v , w) ;
}
int k = Kruskal() ;
if (k == -)
printf("?\n") ;
else
printf("%d\n" , k) ; }
return ;
}
poj 1287
Sample Input
1 0
2 3 //结点 边
1 2 37//u v w
2 1 17
1 2 68
3 7
1 2 19
2 3 11
3 1 7
1 3 5
2 3 89
3 1 91
1 2 32
5 7
1 2 5
2 3 7
2 4 8
4 5 11
3 5 10
1 5 6
4 2 12
0
Sample Output
0
17
16
26
Kruskal
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; int n ;
const int MAXN=;//最大点数
const int MAXM=;//最大边数
int F[MAXN];//并查集使用
struct Edge
{
int u,v,w;
}edge[MAXM];//存储边的信息，包括起点/终点/权值 int tol;//边数，加边前赋值为0
void addedge(int u,int v,int w)
{ edge[tol].u=u;
edge[tol].v=v;
edge[tol++].w=w;
}
bool cmp(Edge a,Edge b)
{//排序函数，讲边按照权值从小到大排序
return a.w<b.w;
}
int find(int x)
{
if(F[x]==-)return x;
else return F[x]=find(F[x]);
}
int Kruskal()//传入点数，返回最小生成树的权值，如果不连通返回-1
{
memset(F,-,sizeof(F));
sort(edge,edge+tol,cmp);
int cnt=;//计算加入的边数
int ans=;
for(int i=;i<tol;i++)
{
int u=edge[i].u;
int v=edge[i].v;
int w=edge[i].w;
int t1=find(u);
int t2=find(v);
if(t1!=t2)
{
ans+=w;
F[t1]=t2;
cnt++;
}
if(cnt==n-)break;
}
if(cnt<n-)return -;//不连通
else return ans;
} int main()
{ //freopen("in.txt","r",stdin) ;
int m ;
while(scanf("%d %d" , &n , &m) != EOF)
{
if (n == )
break ;
int i ;
int u , v , w ;
tol = ;
if (n == && m == )
{
printf("0\n") ;
continue ;
}
while(m--)
{
scanf("%d %d %d" , &u , &v , &w) ;
addedge(u , v , w) ;
}
printf("%d\n" , Kruskal()) ; }
return ;
}
poj 2421
有的路已建 建好了的路权值设为0
Sample Input
3 // n
0 990 692 //邻接矩阵
990 0 179
692 179 0
1 //m
1 2 // u v
Sample Output
179
prim
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; const int INF=0x3f3f3f3f;
const int MAXN=;
bool vis[MAXN];
int lowc[MAXN];
int n ;
int cost[MAXN][MAXN] ; int Prim()//点是0~n-1
{
int ans=;
memset(vis,false,sizeof(vis));
vis[]=true;
for(int i=;i<n;i++)lowc[i]=cost[][i];
for(int i=;i<n;i++)
{
int minc=INF;
int p=-;
for(int j=;j<n;j++)
if(!vis[j]&&minc>lowc[j])
{
minc=lowc[j];
p=j;
}
if(minc==INF)return -;//原图不连通
ans+=minc;
vis[p]=true;
for(int j=;j<n;j++)
if(!vis[j]&&lowc[j]>cost[p][j])
lowc[j]=cost[p][j];
}
return ans;
} int main()
{ // freopen("in.txt","r",stdin) ;
while(cin>>n)
{
int w ;
int i , j ;
for (i = ; i < n ; i++)
for (j = ; j < n ; j++)
{
cin>>w ;
if(w==)
cost[i][j] = INF ;
else
cost[i][j] = w ;
}
int m ;
cin>>m ;
while(m--)
{
int x , y ;
cin>>x>>y ;
cost[x-][y-] = ;
cost[y-][x-] = ;
}
cout<<Prim()<<endl ; }
return ;
}
hdu 1233
n*(n-1)/2条边
Sample Input
3 //n
1 2 1 //u v w
1 3 2
2 3 4
4
1 2 1
1 3 4
1 4 1
2 3 3
2 4 2
3 4 5
0
Sample Output
3
5
Kruskal
# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# define LL long long
using namespace std ; int n ;
const int MAXN=;//最大点数
const int MAXM=;//最大边数
int F[MAXN];//并查集使用
struct Edge
{
int u,v,w;
}edge[MAXM];//存储边的信息，包括起点/终点/权值 int tol;//边数，加边前赋值为0
void addedge(int u,int v,int w)
{ edge[tol].u=u;
edge[tol].v=v;
edge[tol++].w=w;
}
bool cmp(Edge a,Edge b)
{//排序函数，讲边按照权值从小到大排序
return a.w<b.w;
}
int find(int x)
{
if(F[x]==-)return x;
else return F[x]=find(F[x]);
}
int Kruskal()//传入点数，返回最小生成树的权值，如果不连通返回-1
{
memset(F,-,sizeof(F));
sort(edge,edge+tol,cmp);
int cnt=;//计算加入的边数
int ans=;
for(int i=;i<tol;i++)
{
int u=edge[i].u;
int v=edge[i].v;
int w=edge[i].w;
int t1=find(u);
int t2=find(v);
if(t1!=t2)
{
ans+=w;
F[t1]=t2;
cnt++;
}
if(cnt==n-)break;
}
if(cnt<n-)return -;//不连通
else return ans;
} int main()
{ // freopen("in.txt","r",stdin) ;
while(scanf("%d" , &n) != EOF)
{
if (n == )
break ;
int i ;
int u , v , w ;
tol = ; for (i = ; i <= (n-)*n/ ; i++)
{
scanf("%d %d %d" , &u , &v , &w) ;
addedge(u , v , w) ;
}
printf("%d\n" , Kruskal()) ; }
return ;
}