HDU 1162 Eddy's picture (最小生成树)(java版)

Eddy's picture

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

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题目大意：

给你N个点，求把这N个点连在一起的最短总距离。

思路：

假设每两两点之间都有路径，求最小生成树。

AC代码：（Java）

 import java.util.Scanner;
 import java.math.*;
 public class Main {
     public static final int MAXN = 110;
     public static double mp[][] = new double[MAXN][MAXN];
     public static Point p[] = new Point[MAXN];
     public static int n;
     public static String answer = new String();
     public static Scanner scn = new Scanner(System.in);
     public static void main(String[] args){
         for (int i = 0; i < MAXN; i++){
             p[i] = new Point();
         }
         while (scn.hasNext()) {
             n = scn.nextInt();
         foundMap();
         answer = String.format("%.2f", prim());
         System.out.println(answer);
         }
         System.exit(0);
     }
     public static boolean foundMap() {
         double x,y;
         for (int i = 0; i < n; i++) {
             x = scn.nextDouble();
             y = scn.nextDouble();
             p[i].setPoint(x, y);
         }//Found points
         for (int i = 0; i < n; i++)
             for (int j = 0; j < n; j++)
                 if (i != j)
                     mp[i][j] = Point.getDistencs(p[i], p[j]);
         //Found map
         return true;
     }
     public static double prim() {
         int tempI;
         double tempClos;
         double[] closEdge = new double[MAXN];
         double sum = 0.0;
         //Init closeEdge
         closEdge[0] = 0.0;
         for (int i = 1; i < n; i++) {
             closEdge[i] = mp[0][i];
         }
         //Find n-1 edge
         for (int i = 1; i < n; i++) {
             tempI = -1;
             tempClos = -1.0;
             for (int j = 0; j < n; j++) {
                 if (closEdge[j] != 0.0 && (tempClos == -1.0 || closEdge[j] < tempClos)){
                     tempClos = closEdge[j];
                     tempI = j;
                 }
             }
             sum += tempClos;
             closEdge[tempI] = 0;
             for (int j = 0; j < n; j++) {
                 if (j != tempI && closEdge[j] > mp[tempI][j]) {
                     closEdge[j] = mp[tempI][j];
                 }
             }
         }
         return sum;
     }
 }
 class Point { //已下为一个点类 可以不看。
     private double x;
     private double y;
     public Point(double x,double y) {
         this.x = x;
         this.y = y;
     }
     public Point() {
         x = 0.0;
         y = 0.0;
     }
     public void setPoint(double X,double Y) {
         this.x = X;
         this.y = Y;
     }
     public double getX() {
         return x;
     }
     public double getY() {
         return y;
     }
     public static double getDistencs(Point p1,Point p2) {
         return Math.sqrt(Math.pow(p1.getX() - p2.getX(), 2.0) + Math.pow(p1.getY() - p2.getY(),2.0));
     }
 }

2017-07-23 13:07:39