http://acm.hdu.edu.cn/showproblem.php?pid=1162

輸入一個整數n,表示點的個數.

接下來n行,每行有兩個浮點數表示點的x坐標y坐標.

構造一棵最小生成樹.

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用Kruskal做.

先算出各條邊的權值.

再合并

//View Code 1 #include <iostream> 2 #include <algorithm> 3 #include <cmath> 4 using namespace std; 5 const int MAX = 10000 + 10; 6 const int INF = 0x3fffffff; 7 int father[MAX]; 8 int rank1[MAX]; 9 int sign[MAX]; 10 void Make_Set(int x)//初始化 11 { 12 father[x] = x; 13 rank1[x] = 0; 14 } 15 16 int Find_Set(int x)//找根節點 17 { 18 int i=0; 19 while(father[x] != x) 20 { 21 sign[i++] = x; 22 x = father[x]; 23 } 24 for(i;i>=1;i--) 25 { 26 father[sign[i-1]] = x; 27 } 28 return x; 29 } 30 31 void Union(int x,int y)//合并 32 { 33 x = Find_Set(x); 34 y = Find_Set(y); 35 if(x == y) 36 { 37 return; 38 } 39 if(rank1[x] > rank1[y]) 40 { 41 father[y] = x; 42 } 43 else if(rank1[x] < rank1[y]) 44 { 45 father[x] = y; 46 } 47 else if(rank1[x] ==rank1[y]) 48 { 49 father[x] = y; 50 rank1[y]++; 51 } 52 } 53 struct Node 54 { 55 int start; 56 int end; 57 double num; 58 }; 59 bool cmp(Node a,Node b) 60 { 61 return a.num < b.num; 62 } 63 Node num[MAX]; 64 double Kruskal(int n,int m) 65 { 66 int i; 67 for(i=0;i<n;i++) 68 { 69 Make_Set(i); 70 } 71 double sum = 0; 72 int mark = 0; 73 for(i=0;i<m;i++) 74 { 75 int s = Find_Set(num[i].start); 76 int e = Find_Set(num[i].end); 77 if(s != e) 78 { 79 Union(num[i].start,num[i].end); 80 sum += num[i].num; 81 } 82 } 83 return sum; 84 } 85 int main() 86 { 87 int n; 88 while(cin>>n) 89 { 90 double mid_x[MAX],mid_y[MAX]; 91 int i,j; 92 for(i=0;i<n;i++) 93 { 94 cin>>mid_x[i]>>mid_y[i]; 95 } 96 int m = 0; 97 for(i=0;i<n;i++) 98 { 99 for(j=i+1;j<n;j++) 100 { 101 num[m].num = sqrt((mid_x[i]-mid_x[j])*(mid_x[i]-mid_x[j]) + (mid_y[i]-mid_y[j])*(mid_y[i]-mid_y[j])); 102 num[m].start = i; 103 num[m].end = j; 104 m++; 105 } 106 } 107 sort(num,num+m,cmp); 108 printf("%.2lf\n",Kruskal(m,m)); 109 } 110 return 0; 111 }

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轉載于:https://www.cnblogs.com/zxotl/archive/2012/09/06/2674179.html

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