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 }


 
原文地址:https://www.cnblogs.com/shijianming/p/5034739.html