POJ 1502 MPI Maelstrom

题目大意:计算从1开始到其他点的最大距离，主要是输入比较扯拐，是邻接矩阵的下三角

解题思路:Dijkstra，思路是Dijkstra模板题，但是，输入比较扯拐

 1 #include <iostream>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define MAXVERTEXNUM 110
 5 #define INF 1000000
 6 using namespace std;
 7 
 8 int MGraph[MAXVERTEXNUM][MAXVERTEXNUM];
 9 int dist[MAXVERTEXNUM];
10 int Nv;
11 
12 void Dijkstra()
13 {
14     int res = 0;
15     int collected[MAXVERTEXNUM];
16     memset(collected, 0, sizeof(collected));
17 
18     collected[1] = 1;
19     dist[1] = 0;
20     for (int i = 2; i <= Nv; ++i)
21     {
22         if (MGraph[i][1] != INF)
23             dist[i] = MGraph[i][1];
24         else
25             dist[i] = INF;
26     }
27 
28     for (int i = 2; i <= Nv; ++i)
29     {
30         int MinDis = INF, num;
31         for (int j = 2; j <= Nv; ++j)
32             if (!collected[j] && dist[j] < MinDis)
33             {
34                 MinDis = dist[j];
35                 num = j;
36             }
37         if (res < dist[num])
38             res = dist[num];
39         collected[num] = 1;
40 
41         for (int j = 2; j <= Nv; ++j)
42         {
43             if (!collected[j] && dist[j] > dist[num] + MGraph[num][j])
44                 dist[j] = dist[num] + MGraph[num][j];
45         }
46     }
47 
48     cout << res << endl;
49 }
50 
51 int main()
52 {
53     ios::sync_with_stdio(false);
54 
55     cin >> Nv;
56 
57     //init
58     for (int i = 1; i <= Nv; ++i)
59         for (int j = 1; j <= Nv; ++j)
60         {
61             if (i == j)
62                 MGraph[i][j] = 0;
63             else
64                 MGraph[i][j] = INF;
65         }
66 
67     for (int i = 2; i <= Nv; ++i)
68         for (int j = 1; j < i; ++j)
69         {
70             char Edge[1000];
71             memset(Edge, 0, sizeof(Edge));
72             cin >> Edge;
73             int num = 0;
74             if (Edge[0] != 'x')
75             {
76                 for (int i = 0; Edge[i] != '\0'; ++i)
77                     num = num * 10 + Edge[i] - '0';
78             }
79             else
80             {
81                 MGraph[i][j] = MGraph[j][i] = INF;
82                 continue;
83             }
84 
85             MGraph[i][j] = MGraph[j][i] = num;
86         }
87 
88     Dijkstra();
89 
90     return 0;
91 }

 

posted @ 2018-06-28 17:48  duck_lu  阅读(146)  评论(0)  编辑  收藏  举报