• 最短路 之 CODE[VS] 1041 Car的旅行路线 2001年NOIP全国联赛提高组


    
    
    /*
    Floyd算法:最短路
     
    关键:
    	(1)求出矩形第四个点坐标(判断垂直交点,向量加)
    		已知矩形的A、B、C点的坐标,求D点坐标:
    			若 |AB|^2 + |AC|^2 = |BC|^2,则:A点即为垂直交点
    			向量(A->B) + 向量(A->C) = 向量(A->D)
    			=> D.x = A.x + 向量(A->D).x
    			  D.y = A.y + 向量(A->D).y
    	(2)建图
     
    */
      1 #include <iostream>
      2 #include <cstdlib>
      3 #include <cstdio>
      4 #include <cstddef>
      5 #include <iterator>
      6 #include <algorithm>
      7 #include <string>
      8 #include <locale>
      9 #include <cmath>
     10 #include <vector>
     11 #include <cstring>
     12 #include <map>
     13 #include <utility>
     14 #include <queue>
     15 #include <stack>
     16 #include <set>
     17 #include <functional>
     18 using namespace std;
     19 typedef pair<double, int> P; 
     20 const int INF = 0x3f3f3f3f;
     21 const int modPrime = 3046721;
     22 const double eps = 1e-9;
     23 const int MaxN = 105;
     24 
     25 int n, s, A, B;
     26 double t;
     27 double T[MaxN];
     28 
     29 double dp[MaxN][MaxN];
     30 
     31 struct Point
     32 {
     33     int x, y;
     34 };
     35 
     36 vector<Point> cityPoint[MaxN];
     37 
     38 
     39 int disSquare(const Point p1, const Point p2)
     40 {
     41     return (p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y);
     42 }
     43 
     44 int verticalPoint(const Point pt[])
     45 {
     46     int dis01, dis02, dis12;
     47     dis01 = disSquare(pt[0], pt[1]);
     48     dis02 = disSquare(pt[0], pt[2]);
     49     dis12 = disSquare(pt[1], pt[2]);
     50 
     51     if (dis01 + dis02 == dis12) return 0;
     52     if (dis01 + dis12 == dis02) return 1;
     53     if (dis02 + dis12 == dis01) return 2;
     54 
     55     return -1;
     56 }
     57 
     58 void iniCity(int city)
     59 {
     60     Point pt[4];
     61     scanf("%d %d %d %d %d %d %lf", &pt[0].x, &pt[0].y, &pt[1].x, &pt[1].y, &pt[2].x, &pt[2].y, &T[city]);
     62     
     63     int vtcPt = verticalPoint(pt);
     64 
     65     pt[3].x = pt[vtcPt].x + ((pt[(vtcPt + 1) % 3].x - pt[vtcPt].x) + (pt[(vtcPt + 2) % 3].x - pt[vtcPt].x));
     66     pt[3].y = pt[vtcPt].y + ((pt[(vtcPt + 1) % 3].y - pt[vtcPt].y) + (pt[(vtcPt + 2) % 3].y - pt[vtcPt].y));
     67 
     68     for (int i = 0; i < 4; ++i)
     69     {
     70         cityPoint[city].push_back(pt[i]);
     71     }
     72 
     73     for (int i = 0; i < 4; ++i)
     74     {
     75         for (int j = i; j < 4; ++j)
     76         {
     77             if (i != j) 
     78             {
     79                 dp[i + (city << 2)][j + (city << 2)] = T[city] * sqrt(1.0*disSquare(pt[i], pt[j]));
     80                 dp[j + (city << 2)][i + (city << 2)] = dp[i + (city << 2)][j + (city << 2)];
     81             }
     82             else 
     83             {
     84                 dp[i + (city << 2)][j + (city << 2)] = 0.0;
     85             }
     86         }
     87     }
     88 }
     89 
     90 void iniMap()
     91 {
     92     for (int i = 0; i < s; ++i)
     93     {
     94         for (int j = i + 1; j < s; ++j)
     95         {
     96             for (int m = 0; m < 4; ++m)
     97             {
     98                 for (int n = 0; n < 4; ++n)
     99                 {
    100                     dp[m + (i << 2)][n + (j << 2)] = t*sqrt(1.0*disSquare(cityPoint[i][m], cityPoint[j][n]));
    101                     dp[n + (j << 2)][m + (i << 2)] = dp[m + (i << 2)][n + (j << 2)];
    102                 }
    103             }
    104         }
    105     }
    106 }
    107 
    108 void Solve()
    109 {
    110     int pointSum = (s << 2);
    111     for (int k = 0; k < pointSum; ++k)
    112     {
    113         for (int i = 0; i < pointSum; ++i)
    114         {
    115             for (int j = 0; j < pointSum; ++j)
    116             {
    117                 dp[i][j] = min(dp[i][j], dp[i][k] + dp[j][k]);
    118             }
    119         }
    120     }
    121 }
    122 
    123 void getAns()
    124 {
    125     double ans = INF * 1.0;
    126     for (int i = 0; i < 4; ++i)
    127     {
    128         for (int j = 0; j < 4; ++j)
    129         {
    130             ans = min(ans, dp[i + ((A - 1) << 2)][j + ((B - 1) << 2)]);
    131         }
    132     }
    133     printf("%.1lf
    ", ans);
    134 }
    135 
    136 
    137 int main()
    138 {
    139 #ifdef HOME
    140     freopen("in", "r", stdin);
    141     //freopen("out", "w", stdout);
    142 #endif
    143 
    144     scanf("%d", &n);
    145     while (n--)
    146     {
    147         scanf("%d %lf %d %d", &s, &t, &A, &B);
    148         for (int i = 0; i < s; ++i)
    149         {
    150             iniCity(i);
    151         }
    152         iniMap();
    153         Solve();
    154         getAns();
    155         for (int i = 0; i < s; ++i)
    156         {
    157             cityPoint[i].clear();
    158         }
    159     }
    160 
    161 #ifdef HOME
    162     cerr << "Time elapsed: " << clock() / CLOCKS_PER_SEC << " ms" << endl;
    163     _CrtDumpMemoryLeaks();
    164 #endif
    165     return 0;
    166 }
    
    
    
     
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  • 原文地址:https://www.cnblogs.com/shijianming/p/5034739.html
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