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| import java.util.Arrays;
public class Kruskal {
private int edgeNum; private char[] vertexs; private int[][] matrix; private static final int INF = Integer.MAX_VALUE;
public static void main(String[] args) { char[] vertexs = {'A', 'B', 'C', 'D', 'E', 'F', 'G'}; int matrix[][] = { { 0, 12, INF, INF, INF, 16, 14}, { 12, 0, 10, INF, INF, 7, INF}, { INF, 10, 0, 3, 5, 6, INF}, { INF, INF, 3, 0, 4, INF, INF}, { INF, INF, 5, 4, 0, 2, 8}, { 16, 7, 6, INF, 2, 0, 9}, { 14, INF, INF, INF, 8, 9, 0}};
Kruskal kruskalCase = new Kruskal(vertexs, matrix); kruskalCase.print(); kruskalCase.getMinTreeByKruskal();
}
public Kruskal(char[] vertexs, int[][] matrix) { int vlen = vertexs.length;
this.vertexs = new char[vlen]; for (int i = 0; i < vertexs.length; i++) { this.vertexs[i] = vertexs[i]; }
this.matrix = new int[vlen][vlen]; for (int i = 0; i < vlen; i++) { for (int j = 0; j < vlen; j++) { this.matrix[i][j] = matrix[i][j]; } } for (int i = 0; i < vlen; i++) { for (int j = i + 1; j < vlen; j++) { if (this.matrix[i][j] != INF) { edgeNum++; } } }
}
public void getMinTreeByKruskal() { int index = 0; int[] ends = new int[edgeNum]; EData[] rets = new EData[edgeNum];
EData[] edges = getEdges(); System.out.println("图的边的集合=" + Arrays.toString(edges) + " 共" + edges.length);
sortEdges(edges);
for (int i = 0; i < edgeNum; i++) { int p1 = getPosition(edges[i].start); int p2 = getPosition(edges[i].end);
int m = getEnd(ends, p1); int n = getEnd(ends, p2); if (m != n) { ends[m] = n; rets[index++] = edges[i]; } } System.out.println("最小生成树为"); for (int i = 0; i < index; i++) { System.out.println(rets[i]); }
}
public void print() { System.out.println("邻接矩阵为: \n"); for (int i = 0; i < vertexs.length; i++) { for (int j = 0; j < vertexs.length; j++) { System.out.printf("%12d", matrix[i][j]); } System.out.println(); } }
private void sortEdges(EData[] edges) { for (int i = 0; i < edges.length - 1; i++) { for (int j = 0; j < edges.length - 1 - i; j++) { if (edges[j].weight > edges[j + 1].weight) { EData tmp = edges[j]; edges[j] = edges[j + 1]; edges[j + 1] = tmp; } } } }
private int getPosition(char ch) { for (int i = 0; i < vertexs.length; i++) { if (vertexs[i] == ch) { return i; } } return -1; }
private EData[] getEdges() { int index = 0; EData[] edges = new EData[edgeNum]; for (int i = 0; i < vertexs.length; i++) { for (int j = i + 1; j < vertexs.length; j++) { if (matrix[i][j] != INF) { edges[index++] = new EData(vertexs[i], vertexs[j], matrix[i][j]); } } } return edges; }
private int getEnd(int[] ends, int i) { while (ends[i] != 0) { i = ends[i]; } return i; }
}
class EData { char start; char end; int weight;
public EData(char start, char end, int weight) { this.start = start; this.end = end; this.weight = weight; }
@Override public String toString() { return "EData [<" + start + ", " + end + ">= " + weight + "]"; } }
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