poj 1789 Truck History (最小生成树 熟悉两种解法)

prim

#include <iostream>#include <string.h>#include <stdio.h>#include <math.h>#define maxn 3000#define INF 65536using namespace std;int cost[maxn][maxn];bool vis[maxn];int low[maxn];int prim(int n){    int sum=0,p,min;      for(int i=1;i<=n;i++)    vis[i]=false;     vis[1]=true;    for(int i = 1; i <= n; i++)        low[i]=cost[1][i];    for(int i = 2; i <= n; i++)    {        min=INF,p=-1;        for(int j = 1; j <= n; j++)            if(!vis[j]&&min>low[j])            {                min=low[j];                p=j;            }        vis[p]=true;        sum+=min;        for(int j = 1; j <= n; j++)            if(!vis[j]&&low[j]>cost[p][j])                low[j]=cost[p][j];    }    return sum;}int cacluate(char *a,char *b){int count=0;for(int k=0;k<7;k++)if(a[k]!=b[k])count++;return count;}int main(int argc, char const *argv[]){int n;char str[maxn][9];while(scanf("%d",&n)!=EOF){if(n==0)break;for(int i = 1; i <= n; i++)scanf("%s",str[i]);for(int i=1;i<=n;i++){for(int j=i;j<=n;j++)cost[i][j]=cost[j][i]=cacluate(str[i],str[j]);}cout<<"The highest possible quality is 1/"<<prim(n)<<"."<<endl;}return 0;}

Kruskal

#include <iostream>#include <stdio.h>#include <algorithm>#include <string.h>#include <math.h>#include <stdlib.h>#define maxn 2010#define maxm 2000*2000+10using namespace std;int father[maxn];int r[maxn];char str[maxn][maxn];struct Edge{int u,v;int weight;};Edge edge[maxm];int cmp(Edge a,Edge b){return a.weight<b.weight;}int find(int v){if(v==father[v])return v;return father[v]=find(father[v]);}void join(int u,int v){int a=find(u);int b=find(v);if(a==b)return ;if(r[a]<r[b])father[a]=b;else if(r[b]<r[a])father[b]=a;else{father[a]=b;r[b]++;}}int Kruskal(int n,int m){sort(edge,edge+m,cmp);int sum=0,cnt=0;for(int i=0;i<m;i++){int u=edge[i].u;int v=edge[i].v;if(find(u)!=find(v)){cnt++;sum+=edge[i].weight;father[find(u)]=find(v);join(u,v);}if(n-1==cnt)return sum;}return -1;}int cacluate(char *a,char *b){int count = 0;for(int k=0;k<7;k++)if(a[k]!=b[k])count++;return count;}int main(){    int n;    while(cin>>n&&n)    {        for(int i=1;i<=n;i++)        scanf("%s",str[i]);        for(int i=1;i<=n;i++)        {        father[i]=i;        r[i]=i;        }        int res=1;        for(int i=1;i<=n;i++)        {        for(int j=i+1;j<=n;j++)        {            edge[res].u=i;            edge[res].v=j;            edge[res++].weight=cacluate(str[i],str[j]);        }    }        cout<<"The highest possible quality is 1/"<<Kruskal(n,res)<<"."<<endl;    }return 0;}

kuaskal用qsort过不了，用sort就过。。。。。。