标签:tar target 添加 必须 targe 连接 class tor block
转自:勿在浮沙筑高台http://blog.csdn.net/luoshixian099/article/details/51908175
关于图的几个概念定义:
下面介绍两种求最小生成树算法
此算法可以称为“加边法”,初始最小生成树边数为0,每迭代一次就选择一条满足条件的最小代价边,加入到最小生成树的边集合里。
1. 把图中的所有边按代价从小到大排序;
2. 把图中的n个顶点看成独立的n棵树组成的森林;
3. 按权值从小到大选择边,所选的边连接的两个顶点ui,vi应属于两颗不同的树,则成为最小生成树的一条边,并将这两颗树合并作为一颗树。
4. 重复(3),直到所有顶点都在一颗树内或者有n-1条边为止。
此算法可以称为“加点法”,每次迭代选择代价最小的边对应的点,加入到最小生成树中。算法从某一个顶点s开始,逐渐长大覆盖整个连通网的所有顶点。
由于不断向集合u中加点,所以最小代价边必须同步更新;需要建立一个辅助数组closedge,用来维护集合v中每个顶点与集合u中最小代价边信息,:
struct { char vertexData //表示u中顶点信息 UINT lowestcost //最小代价 }closedge[vexCounts]
#include <iostream> #include <vector> #include <queue> #include <algorithm> using namespace std; #define INFINITE 0xFFFFFFFF #define VertexData unsigned int //顶点数据 #define UINT unsigned int #define vexCounts 6 //顶点数量 char vextex[] = { ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ }; struct node { VertexData data; unsigned int lowestcost; }closedge[vexCounts]; //Prim算法中的辅助信息 typedef struct { VertexData u; VertexData v; unsigned int cost; //边的代价 }Arc; //原始图的边信息 void AdjMatrix(unsigned int adjMat[][vexCounts]) //邻接矩阵表示法 { for (int i = 0; i < vexCounts; i++) //初始化邻接矩阵 for (int j = 0; j < vexCounts; j++) { adjMat[i][j] = INFINITE; } adjMat[0][1] = 6; adjMat[0][2] = 1; adjMat[0][3] = 5; adjMat[1][0] = 6; adjMat[1][2] = 5; adjMat[1][4] = 3; adjMat[2][0] = 1; adjMat[2][1] = 5; adjMat[2][3] = 5; adjMat[2][4] = 6; adjMat[2][5] = 4; adjMat[3][0] = 5; adjMat[3][2] = 5; adjMat[3][5] = 2; adjMat[4][1] = 3; adjMat[4][2] = 6; adjMat[4][5] = 6; adjMat[5][2] = 4; adjMat[5][3] = 2; adjMat[5][4] = 6; } int Minmum(struct node * closedge) //返回最小代价边 { unsigned int min = INFINITE; int index = -1; for (int i = 0; i < vexCounts;i++) { if (closedge[i].lowestcost < min && closedge[i].lowestcost !=0) { min = closedge[i].lowestcost; index = i; } } return index; } void MiniSpanTree_Prim(unsigned int adjMat[][vexCounts], VertexData s) { for (int i = 0; i < vexCounts;i++) { closedge[i].lowestcost = INFINITE; } closedge[s].data = s; //从顶点s开始 closedge[s].lowestcost = 0; for (int i = 0; i < vexCounts;i++) //初始化辅助数组 { if (i != s) { closedge[i].data = s; closedge[i].lowestcost = adjMat[s][i]; } } for (int e = 1; e <= vexCounts -1; e++) //n-1条边时退出 { int k = Minmum(closedge); //选择最小代价边 cout << vextex[closedge[k].data] << "--" << vextex[k] << endl;//加入到最小生成树 closedge[k].lowestcost = 0; //代价置为0 for (int i = 0; i < vexCounts;i++) //更新v中顶点最小代价边信息 { if ( adjMat[k][i] < closedge[i].lowestcost) { closedge[i].data = k; closedge[i].lowestcost = adjMat[k][i]; } } } } void ReadArc(unsigned int adjMat[][vexCounts],vector<Arc> &vertexArc) //保存图的边代价信息 { Arc * temp = NULL; for (unsigned int i = 0; i < vexCounts;i++) { for (unsigned int j = 0; j < i; j++) { if (adjMat[i][j]!=INFINITE) { temp = new Arc; temp->u = i; temp->v = j; temp->cost = adjMat[i][j]; vertexArc.push_back(*temp); } } } } bool compare(Arc A, Arc B) { return A.cost < B.cost ? true : false; } bool FindTree(VertexData u, VertexData v,vector<vector<VertexData> > &Tree) { unsigned int index_u = INFINITE; unsigned int index_v = INFINITE; for (unsigned int i = 0; i < Tree.size();i++) //检查u,v分别属于哪颗树 { if (find(Tree[i].begin(), Tree[i].end(), u) != Tree[i].end()) index_u = i; if (find(Tree[i].begin(), Tree[i].end(), v) != Tree[i].end()) index_v = i; } if (index_u != index_v) //u,v不在一颗树上,合并两颗树 { for (unsigned int i = 0; i < Tree[index_v].size();i++) { Tree[index_u].push_back(Tree[index_v][i]); } Tree[index_v].clear(); return true; } return false; } void MiniSpanTree_Kruskal(unsigned int adjMat[][vexCounts]) { vector<Arc> vertexArc; ReadArc(adjMat, vertexArc);//读取边信息 sort(vertexArc.begin(), vertexArc.end(), compare);//边按从小到大排序 vector<vector<VertexData> > Tree(vexCounts); //6棵独立树 for (unsigned int i = 0; i < vexCounts; i++) { Tree[i].push_back(i); //初始化6棵独立树的信息 } for (unsigned int i = 0; i < vertexArc.size(); i++)//依次从小到大取最小代价边 { VertexData u = vertexArc[i].u; VertexData v = vertexArc[i].v; if (FindTree(u, v, Tree))//检查此边的两个顶点是否在一颗树内 { cout << vextex[u] << "---" << vextex[v] << endl;//把此边加入到最小生成树中 } } } int main() { unsigned int adjMat[vexCounts][vexCounts] = { 0 }; AdjMatrix(adjMat); //邻接矩阵 cout << "Prim :" << endl; MiniSpanTree_Prim(adjMat,0); //Prim算法,从顶点0开始. cout << "-------------" << endl << "Kruskal:" << endl; MiniSpanTree_Kruskal(adjMat);//Kruskal算法 return 0; }
标签:tar target 添加 必须 targe 连接 class tor block
原文地址:https://www.cnblogs.com/zhangzefei/p/9750300.html