CCF系列之最优灌溉(201412-4)

 1 package ccf_text2014_12;
 2 
 3 import java.util.Scanner;
 4 
 5 public class BestGuanGai2 {
 6     
 7     static final int MAX = Integer.MAX_VALUE;
 8 
 9     static int primAlgorithm(int[][] graphMatrix, int vertexNumber, int initialVertex) {
10         int minCost = 0;
11         boolean[] visited = new boolean[vertexNumber + 1];
12         for (int i = 0; i < vertexNumber + 1; i++) {
13             visited[i] = false;
14         }
15 
16         int position = initialVertex;
17         visited[position] = true;
18         int[] lowCostInLine = new int[vertexNumber + 1];
19         int min = MAX;
20 
21         for (int i = 1; i < vertexNumber + 1; i++) {
22             lowCostInLine[i] = graphMatrix[position][i];
23         }
24         for (int i = 1; i < vertexNumber; i++) {
25             for (int j = 1; j < vertexNumber + 1; j++) {
26                 if (visited[j] == false && lowCostInLine[j] < min) {
27                     min = lowCostInLine[j];
28                     position = j;
29                 }
30             }
31             minCost += min;
32             min = MAX;
33             visited[position] = true;
34             for (int j = 1; j < vertexNumber + 1; j++) {
35                 if (visited[j] == false && graphMatrix[position][j] < lowCostInLine[j]) {
36                     lowCostInLine[j] = graphMatrix[position][j];
37                 }
38             }
39         }
40         return minCost;
41     }
42 
43     public static void main(String[] args) {
44         Scanner sc = new Scanner(System.in);
45         int n, m;
46         n = sc.nextInt();
47         m = sc.nextInt();
48         int[][] adjMatrix = new int[n + 1][n + 1];
49         int result = 0;
50 
51         for (int i = 1; i < n + 1; i++) {
52             for (int j = 1; j < n + 1; j++) {
53                 adjMatrix[i][j] = MAX;
54             }
55         }
56         for (int i = 0; i < m; i++) {
57             int begin = sc.nextInt();
58             int end = sc.nextInt();
59             int weight = sc.nextInt();
60             adjMatrix[begin][end] = weight;
61             adjMatrix[end][begin] = weight;
62         }
63         result = primAlgorithm(adjMatrix, n, 4);
64         System.out.println(result);
65     }
66 }