POJ 1289 解題報告

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Kruskal code

#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std; 
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val)	 memset(var,val,sizeof(var))
#define LL long long 
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x)   rand()%(x)
#define lowbit(x)   x&(-x)
inline int read()
{
	int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
	while ( a>='0' && a<='9' ){	x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 10005
int dis[N],tot,ans; 
int fa[N];
bool vis[N];
int n;  
int findfa(int x){
	int p = x,temp; 
	while ( p != fa[p]){
		p = fa[p];
	}
	while ( x != p ){
		temp = fa[x];
		fa[ x ] = p ; 
		x = temp ; 	
	} 
	return fa[x];
}
struct Edge{
	int u,v,w; 
}e[N];
bool cmp(Edge a,Edge b){
	return a.w < b.w; 
}
void kruskal(){
	int cnt = 0; 
	sort(e+1,e+tot+1,cmp);
	rep(aai,1,tot){
		int ufa = findfa(e[aai].u);
		int vfa = findfa(e[aai].v);
		if ( ufa != vfa ){
			fa[ufa] = vfa; 
			ans += e[aai].w; 
			cnt++;
		}
		if ( cnt == n-1 )
			break; 
	}
}
int main()
{
//	freopen("1.txt","r",stdin);
	srand((int)time(0));
//	std::ios::sync_with_stdio(false);
	while ( scanf("%d",&n) != EOF && n ){
		mset(e,0x3f); 
		rep(i,0,N-1) fa[i] = i; 
		tot = 0; ans = 0; 
		scanf("%d",&tot);
		rep(i,1,tot){
            scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].w);    			
		}
		sort(e+1,e+tot+1,cmp);	
		kruskal();
		cout<<ans<<endl; 
	}
	return 0;
}

prim code

#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std; 
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val)	 memset(var,val,sizeof(var))
#define LL long long 
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x)   rand()%(x)
#define lowbit(x)   x&(-x)
inline int read()
{
	int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
	while ( a>='0' && a<='9' ){	x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 105
int dis[N],tot,ans; 
int fa[N];
bool vis[N];
int n;  
int findfa(int x){
	int p = x,temp; 
	while ( p != fa[p]){
		p = fa[p];
	}
	while ( x != p ){
		temp = fa[x];
		fa[ x ] = p ; 
		x = temp ; 	
	} 
	return fa[x];
}
int e[N][N];

void prim(){
	int minx,v; 
	rep(i,0,n)	dis[i] = e[1][i], vis[i] = 0; 
	rep(ai,1,n){
		minx = inf; 
		rep(bi,1,n)	if ( !vis[bi] && dis[bi] < minx )			minx = dis[bi] , v = bi; 
		vis[ v ] = 1;
		rep(bi,1,n)	if ( !vis[bi] && dis[bi] > e[v][bi] )		dis[bi] = e[v][bi];
	}
	rep(i,1,n)	ans += dis[i];
}
int main()
{
//	freopen("1.txt","r",stdin);
	srand((int)time(0));
//	std::ios::sync_with_stdio(false);
	while ( scanf("%d",&n) != EOF && n ){
		mset(e,0x3f); 
		rep(i,0,N-1) fa[i] = i,e[i][i]=0; 
		tot = 0; ans = 0; 
		scanf("%d",&tot);
		rep(i,1,tot){
 			int u,v,w ; 
			u = read(); v = read(); w = read();
			e[u][v] = e[v][u] = min(w,min(e[v][u],e[u][v])); 
		}	
		prim();
		cout<<ans<<endl; 
	}
	return 0;
}