POJ 1258 Agri-Net(最小產生樹)

//Kruskal + 並查集<br />#include<iostream><br />#include<algorithm><br />using namespace std;<br />int fa[101];//父親指標數組<br />int G[105][105];//圖<br />int n,e;//點數和邊數<br />struct edge//存放邊的結構體<br />{<br />int u;<br />int v;<br />int w;<br />}E[5000];<br />bool cmp(edge a,edge b)//對邊權進行排序的排序比較函數<br />{<br />return a.w < b.w;<br />}<br />int getfather(int x)//取得父親函數<br />{<br />return fa[x] == x ? x : fa[x] = getfather(fa[x]);<br />}<br />int Kruskal(int e)<br />{<br />int ans = 0;<br />for(int i = 0;i < n;++i)<br />fa[i] = i;<br />sort(E,E+e,cmp);<br />for(int i = 0;i < e;++i)<br />{<br />int x = getfather(E[i].u);<br />int y = getfather(E[i].v);<br />if(x != y)<br />{<br />ans += E[i].w;<br />fa[x] = y;<br />}<br />}<br />return ans;<br />}<br />int main()<br />{<br />//freopen("in.txt","r",stdin);<br />while(scanf("%d",&n) != EOF)<br />{<br />for(int i = 0;i < n;++i)<br />for(int j = 0;j < n;++j)<br />scanf("%d",&G[i][j]);<br />int e = 0;<br />for(int i = 0;i < n-1;++i)<br />{<br />for(int j = i+1;j < n;++j)<br />{<br />E[e].u = i;<br />E[e].v = j;<br />E[e++].w = G[i][j];<br />}<br />}//讀邊<br />printf("%d/n",Kruskal(e));<br />}<br />return 0;<br />}