1 #include<cstdio> 2 #include<cstring> 3 #include<cmath> 4 #include<iostream> 5 #include<algorithm> 6 #include<queue> 7 #include<set> 8 #define maxint (2147483647) 9 #define l(a) ((a)<<1) 10 #define r(a) ((a)<<1|1) 11 #define b(a) (2<<(a)) 12 #define rep(i,a,b) for(int i=a;i<=(b);i++) 13 #define clr(a) memset(a,0,sizeof(a)) 14 typedef long long ll; 15 using namespace std; 16 int readint(){ 17 int t=0,f=1;char c=getchar(); 18 while(!isdigit(c)){ 19 if(c=='-') f=-1; 20 c=getchar(); 21 } 22 while(isdigit(c)){ 23 t=(t<<3)+(t<<1)+c-'0'; 24 c=getchar(); 25 } 26 return t*f; 27 } 28 const int maxn=5009,maxm=200009; 29 struct edge{ 30 int u,v,w; 31 inline bool operator <(edge E)const{ 32 return w<E.w; 33 } 34 }e[maxm]; 35 int n,m,f[maxn]; 36 int find(int x){ 37 if(f[x]==x) return f[x]; 38 return f[x]=find(f[x]); 39 } 40 int kruskal(){ 41 int ans=0; 42 sort(e+1,e+m+1); 43 rep(i,1,n) f[i]=i; 44 rep(i,1,m){ 45 if(find(e[i].u)!=find(e[i].v)){ 46 f[find(e[i].u)]=find(e[i].v); 47 ans+=e[i].w; 48 } 49 } 50 return ans; 51 } 52 int main(){ 53 //freopen("#input.txt","r",stdin); 54 //freopen("#output.txt","w",stdout); 55 n=readint();m=readint(); 56 rep(i,1,m){ 57 e[i].u=readint(); 58 e[i].v=readint(); 59 e[i].w=readint(); 60 } 61 cout<<kruskal()<<endl; 62 //fclose(stdin); 63 //fclose(stdout); 64 return 0; 65 }
1 #include<cstdio> 2 #include<cstring> 3 #include<cmath> 4 #include<ctime> 5 #include<iostream> 6 #include<algorithm> 7 #include<queue> 8 #include<set> 9 #define maxint (2147483647) 10 #define l(a) ((a)<<1) 11 #define r(a) ((a)<<1|1) 12 #define b(a) (1<<(a)) 13 #define rep(i,a,b) for(int i=a;i<=(b);i++) 14 #define clr(a) memset(a,0,sizeof(a)) 15 typedef long long ll; 16 using namespace std; 17 int readint(){ 18 int t=0,f=1;char c=getchar(); 19 while(!isdigit(c)){ 20 if(c=='-') f=-1; 21 c=getchar(); 22 } 23 while(isdigit(c)){ 24 t=(t<<3)+(t<<1)+c-'0'; 25 c=getchar(); 26 } 27 return t*f; 28 } 29 ll readll(){ 30 ll t=0ll,f=1ll;char c=getchar(); 31 while(!isdigit(c)){ 32 if(c=='-') f=-1ll; 33 c=getchar(); 34 } 35 while(isdigit(c)){ 36 t=(t<<3ll)+(t<<1ll)+ll(c-'0'); 37 c=getchar(); 38 } 39 return t*f; 40 } 41 struct edge{ 42 int v,w; 43 edge*next; 44 inline edge(int V,int W){ 45 v=V;w=W; 46 } 47 inline edge(){} 48 inline bool operator<(const edge E)const{ 49 return w>E.w||(w==E.w&&v>E.v); 50 } 51 }; 52 const int maxn=1009,maxm=50009; 53 int n,m,t,ans; 54 bool p[maxn]; 55 edge e[maxm],*pt=e,*fir[maxn]; 56 priority_queue<edge>Q; 57 void add(int u,int v,int w){ 58 pt->v=v;pt->w=w;pt->next=fir[u]; 59 fir[u]=pt++; 60 } 61 void Dfs(int x){ 62 p[x]=1; 63 for(edge*E=fir[x];E;E=E->next) if(!p[E->v]) Q.push(*E); 64 while(!Q.empty()&&p[Q.top().v]) Q.pop(); 65 if(Q.empty()) return; 66 edge E=Q.top();Q.pop(); 67 ans+=E.w; 68 Dfs(E.v); 69 } 70 int main(){ 71 //freopen("#input.txt","r",stdin); 72 //freopen("#output.txt","w",stdout); 73 n=readint();m=readint(); 74 rep(i,1,m){ 75 int u=readint(),v=readint(),w=readint(); 76 add(u,v,w);add(v,u,w);t+=w; 77 } 78 Dfs(1); 79 cout<<ans<<endl; 80 //fclose(stdin); 81 //fclose(stdout); 82 return 0; 83 }
MST问题中注意加双向边！！！
上面的prim姿势好像有问题
1 #include<cstdio> 2 #include<cstring> 3 #include<cmath> 4 #include<ctime> 5 #include<iostream> 6 #include<algorithm> 7 #include<queue> 8 #include<set> 9 #define inf (0x7fffffff) 10 #define l(a) ((a)<<1) 11 #define r(a) ((a)<<1|1) 12 #define b(a) (1<<(a)) 13 #define rep(i,a,b) for(int i=a;i<=(b);i++) 14 #define clr(a) memset(a,0,sizeof(a)) 15 typedef long long ll; 16 typedef unsigned long long ull; 17 using namespace std; 18 int readint(){ 19 int t=0,f=1;char c=getchar(); 20 while(!isdigit(c)){ 21 if(c=='-') f=-1; 22 c=getchar(); 23 } 24 while(isdigit(c)){ 25 t=(t<<3)+(t<<1)+c-'0'; 26 c=getchar(); 27 } 28 return t*f; 29 } 30 const int maxn=5009; 31 struct node{ 32 double x,y; 33 inline void in(){ 34 x=readint();y=readint(); 35 } 36 }x[maxn]; 37 double dis(int a,int b){ 38 return sqrt((x[a].x-x[b].x)*(x[a].x-x[b].x)+(x[a].y-x[b].y)*(x[a].y-x[b].y)); 39 } 40 struct edge{ 41 int v; 42 double w; 43 inline edge(int V,double W){ 44 v=V;w=W; 45 } 46 inline bool operator<(const edge A)const{ 47 return w>A.w; 48 } 49 }; 50 int n; 51 double ans,d[maxn]; 52 bool p[maxn]; 53 priority_queue<edge>Q; 54 void cal(){ 55 int cnt=0; 56 rep(i,1,n) d[i]=1e10;d[1]=0;Q.push(edge(1,0)); 57 while(!Q.empty()){ 58 while(p[Q.top().v]) Q.pop(); 59 edge e=Q.top();Q.pop(); 60 cnt++;p[e.v]=1;ans+=e.w; 61 if(cnt==n) break; 62 rep(i,1,n) if(!p[i]){ 63 double tmp=dis(i,e.v); 64 if(d[i]>tmp){ 65 Q.push(edge(i,tmp)); 66 d[i]=tmp; 67 } 68 } 69 } 70 printf("%.2lf ",ans); 71 } 72 int main(){ 73 //freopen("#input.txt","r",stdin); 74 //freopen("#output.txt","w",stdout); 75 n=readint(); 76 rep(i,1,n) x[i].in(); 77 cal(); 78 //fclose(stdin); 79 //fclose(stdout); 80 return 0; 81 }