POJ 1258 Agri-Net (prim + kruskal)

最小生成树水题，不解释。两种方法，没有用priority queue优化。

PRIM：

 

#include<iostream>const int INF = 99999999;using namespace std;int main(void){int map[101][101];int dist[101],flag[101];int n,i,j;int now,min,sum;while( cin >> n){for( i = 1;i <= n;i++){dist[i] = INF;flag[i] = 0;for( j = 1; j <= n; j++ ) cin >> map[i][j];}sum = 0;dist[1] = 0;flag[now=1] = 1;for( i = 1; i < n; i++ ){for( j = 1; j <= n; j++ )if( !flag[j] && map[now][j] < dist[j] )dist[j] = map[now][j];for( j = 1,min = INF; j <= n; j++ )if( !flag[j] && dist[j] < min)min = dist[ now = j ];flag[now] = 1;sum += min;}cout << sum << endl;}return 0;}

 

KRUSKAL：

#include<iostream>#include<algorithm>const int INF = 99999999;using namespace std;struct node{int from,to,w;} edge[10001],t;int p[101];int find(int x){return p[x]==x?x:p[x]=find(p[x]);}int cmp(const node a,const node b){return a.w<b.w;}int main(void){int map[101][101];int dist[101],flag[101];int n,i,j,from,to;int now,min,sum,count;while( cin >> n){for( i = 1,count = 0; i <= n; i++ )for( j = 1; j <= n; j++ ){count++;edge[count].from = i;edge[count].to = j;cin >> edge[count].w;}sort(edge+1,edge+count+1,cmp);sum = 0;for( i = 1; i <= n; i++ ) p[i] = i;for( i = 1,min=0; i <= count; i++ ){from = edge[i].from;to = edge[i].to;from = find(from);to = find(to);if( from == to ) continue;sum += edge[i].w;p[from] = to;++min;if( min == n-1) break;}cout << sum << endl;}return 0;}