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还是畅通工程Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 29254 Accepted Submission(s): 13088
Problem Description
某省调查乡村交通状况,得到的统计表中列出了任意两村庄间的距离。省政府“畅通工程”的目标是使全省任何两个村庄间都可以实现公路交通(但不一定有直接的公路相连,只要能间接通过公路可达即可),并要求铺设的公路总长度为最小。请计算最小的公路总长度。
Input
测试输入包含若干测试用例。每个测试用例的第1行给出村庄数目N ( < 100 );随后的N(N-1)/2行对应村庄间的距离,每行给出一对正整数,分别是两个村庄的编号,以及此两村庄间的距离。为简单起见,村庄从1到N编号。
当N为0时,输入结束,该用例不被处理。
Output
对每个测试用例,在1行里输出最小的公路总长度。
Sample Input
3
1 2 1
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
Hint
Hint
Huge input, scanf is recommended.
Source
浙大计算机研究生复试上机考试-2006年
prim 算法
//#include<bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<string>
#include<queue>
#include<vector>
#include<map>
#include<cstdlib>
#include<set>
#include<stack>
#include<cstring>
using namespace std;
template<class T>inline T read(T&x)
{char c;while((c=getchar())<=32)if(c==EOF)return -1;bool ok=false;if(c=='-')ok=true,c=getchar();for(x=0; c>32; c=getchar())x=x*10+c-'0';if(ok)x=-x;return 1;
}
template<class T> inline T read_(T&x,T&y)
{return read(x)!=-1&&read(y)!=-1;
}
template<class T> inline T read__(T&x,T&y,T&z)
{return read(x)!=-1&&read(y)!=-1&&read(z)!=-1;
}
template<class T> inline void write(T x)
{if(x<0)putchar('-'),x=-x;if(x<10)putchar(x+'0');else write(x/10),putchar(x%10+'0');
}
template<class T>inline void writeln(T x)
{write(x);putchar('\n');
}
//-------ZCC IO template------
const int maxn=101;
const double inf=999999999;
#define lson (rt<<1),L,M
#define rson (rt<<1|1),M+1,R
#define M ((L+R)>>1)
#define For(i,t,n) for(int i=(t);i<(n);i++)
typedef long long LL;
typedef double DB;
typedef pair<int,int> P;
#define bug printf("---\n");
#define mod 10007int G[maxn][maxn];
int vis[maxn];
int mincost[maxn];
int V,E;
void prim()
{For(i,0,V+1){mincost[i]=inf;vis[i]=false;}mincost[1]=0;int ans=0;while(true){int v=-1;For(u,1,V+1)if(!vis[u]&&(v==-1||mincost[v]>mincost[u]))v=u;if(v==-1)break;vis[v]=true;ans+=mincost[v];For(u,1,V+1)mincost[u]=min(mincost[u],G[v][u]);}writeln(ans);
}
int main()
{//#ifndef ONLINE_JUDGE//freopen("in.txt","r",stdin);// #endif // ONLINE_JUDGEint n,m,i,j,k,t;while(read(V)&&V){E=V*(V-1)/2;while(E--){int a,b,c;read__(a,b,c);G[a][b]=G[b][a]=c;}prim();}return 0;
}
Kruskal算法
//#include<bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<string>
#include<queue>
#include<vector>
#include<map>
#include<cstdlib>
#include<set>
#include<stack>
#include<cstring>
using namespace std;
template<class T>inline T read(T&x)
{char c;while((c=getchar())<=32)if(c==EOF)return -1;bool ok=false;if(c=='-')ok=true,c=getchar();for(x=0; c>32; c=getchar())x=x*10+c-'0';if(ok)x=-x;return 1;
}
template<class T> inline T read_(T&x,T&y)
{return read(x)!=-1&&read(y)!=-1;
}
template<class T> inline T read__(T&x,T&y,T&z)
{return read(x)!=-1&&read(y)!=-1&&read(z)!=-1;
}
template<class T> inline void write(T x)
{if(x<0)putchar('-'),x=-x;if(x<10)putchar(x+'0');else write(x/10),putchar(x%10+'0');
}
template<class T>inline void writeln(T x)
{write(x);putchar('\n');
}
//-------ZCC IO template------
const int maxn=101;
const double inf=999999999;
#define lson (rt<<1),L,M
#define rson (rt<<1|1),M+1,R
#define M ((L+R)>>1)
#define For(i,t,n) for(int i=(t);i<(n);i++)
typedef long long LL;
typedef double DB;
typedef pair<int,int> P;
#define bug printf("---\n");
#define mod 10007
struct edge
{int from,to,cost;edge(){}edge(int a,int b,int c){from=a,to=b,cost=c;}bool operator<(const edge&tmp)const{return cost<tmp.cost;}
}es[maxn*maxn];int f[maxn];
void init(int n)
{For(i,0,n+1)f[i]=i;
}
int find(int x)
{return x==f[x]?x:(f[x]=find(f[x]));
}
void unio(int x,int y)
{x=find(x);y=find(y);if(x==y)return ;f[x]=y;
}
bool same(int x,int y)
{return find(x)==find(y);
}
int main()
{//#ifndef ONLINE_JUDGE//freopen("in.txt","r",stdin);// #endif // ONLINE_JUDGEint n,m,i,j,k,t;int V,E;while(read(V)&&V){E=V*(V-1)/2;for(i=0;i<E;i++){int a,b,c;read__(a,b,c);es[i]=edge(a,b,c);}init(V);sort(es,es+E);int ans=0;for(i=0;i<E;i++){edge e=es[i];if(!same(e.to,e.from)){ans+=e.cost;unio(e.to,e.from);}}writeln(ans);}return 0;
}
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