次小生成树模板(poj1679)
prim
#include <iostream> #include <cstdio> #include <cstdlib> #include <cmath> #include <algorithm> #include <cstring> #include <stack> #include <cctype> #include <queue> #include <string> #include <vector> #include <set> #include <map> #include <climits> #define lson root<<1,l,mid #define rson root<<1|1,mid+1,r #define fi first #define se second #define ping(x,y) ((x-y)*(x-y)) #define mst(x,y) memset(x,y,sizeof(x)) #define mcp(x,y) memcpy(x,y,sizeof(y)) #define Min(x,y) (x<y?x:y) #define Max(x,y) (x>y?x:y) using namespace std; #define gamma 0.5772156649015328606065120 //欧拉常数 #define MOD 100000007 #define inf 0x3f3f3f3f #define N 205 #define maxn 10001000 typedef long long LL; typedef pair<int,int> PII; int vis[105],d[105],pic[105][105],used[105][105],path[105][105]; int ans,n,pre[105]; int prim() { for(int i=1; i<=n; ++i) pre[i]=1; mst(vis,0); vis[1]=1; int res=0; int i,j; for(i=1; i<=n; ++i) d[i]=pic[1][i]; for(i=1; i<n; ++i) { int m=inf,u; for(j=2; j<=n; ++j) if(!vis[j]&&d[j]<m) m=d[u=j]; res+=m; vis[u]=1; used[u][pre[u]]=used[pre[u]][u]=1; for(j=1; j<=n; ++j) if(!vis[j]&&pic[u][j]<d[j]) {d[j]=pic[u][j];pre[j]=u;} else if(vis[j]&&j!=u) path[j][u]=path[u][j]=Max(m,path[j][pre[u]]); } int temp=inf; for(int i=1; i<=n; ++i) for(int j=i+1; j<=n; ++j) { if(!used[i][j]) temp=Min(temp,res+pic[i][j]-path[i][j]); } if(temp==res) return 0; ans=res; return 1; } int main() { //freopen("in.txt","r",stdin); int i,j,x,y,v,group,m; scanf("%d",&group); while(group--) { scanf("%d%d",&n,&m); mst(path,0); mst(pic,inf); mst(used,0); for(i=0; i<m; ++i) { scanf("%d%d%d",&x,&y,&v); pic[x][y]=pic[y][x]=v; } ans=0; if(prim()) printf("%d\n",ans); else printf("Not Unique!\n"); } return 0; }
kruskal:
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <stack>
#include <cctype>
#include <queue>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <climits>
#define lson root<<1,l,mid
#define rson root<<1|1,mid+1,r
#define fi first
#define se second
#define ping(x,y) ((x-y)*(x-y))
#define mst(x,y) memset(x,y,sizeof(x))
#define mcp(x,y) memcpy(x,y,sizeof(y))
#define Min(x,y) (x<y?x:y)
#define Max(x,y) (x>y?x:y)
using namespace std;
#define gamma 0.5772156649015328606065120
#define MOD 100000007
#define inf 0x3f3f3f3f
#define N 100005
#define maxn 1000050
typedef long long LL;
typedef pair<int,int> PII;
int n,m,cnt,vis[6000],fp[105]; ///vis[]是标记第一次求mst时用过哪些边(后面枚举删边时用到)
struct Node{
int x,y,v;
bool operator<(const Node&a)const{
return v<a.v;
}
Node(){}
Node(int a,int b,int c):x(a),y(b),v(c){}
}node[6000];
int findp(int x){return fp[x]==x?x:fp[x]=findp(fp[x]);}
int kus(int xx){ ///xx表示删除哪条边
int res=0;
for(int i=0;i<=n;++i)fp[i]=i;
int num=1;
for(int i=0;i<cnt;++i){
if(i==xx)continue;
int x=findp(node[i].x);
int y=findp(node[i].y);
if(x==y)continue;
res+=node[i].v;
fp[x]=y;
if(xx==inf)vis[i]=1;
if(++num==n)break;
}
if(num<n)return inf;
else return res;
}
int main(){
int x,y,v,i,j,group,Case=0,m;
//freopen("in.txt","r",stdin);
scanf("%d",&group);
while(group--){
mst(vis,0);
scanf("%d%d",&n,&m);
cnt=0;
while(m--){
scanf("%d%d%d",&x,&y,&v);
node[cnt++]=Node(x,y,v);
}
sort(node,node+cnt);
int res=kus(inf),ans=inf;
for(i=0;i<cnt;++i){
if(vis[i])
ans=Min(ans,kus(i));
}
if(ans==res)printf("Not Unique!\n");
else printf("%d\n",res);
}
return 0;
}