Bessie Come Home chapter 2.4

第一次用dijkstra做题,思路很清晰,但是写完发现竟然有130行...调试都调了好一会

看了看别人同是用dijkstra做,不到50行,压力山大,看来以后做对了也得看看别人的题解

  1 /*
  2 
  3 ID: hubiao cave
  4 
  5 PROG: comehome
  6 
  7 LANG: C++
  8 
  9 */
 10 
 11 
 12 
 13 
 14 #include<iostream>
 15 
 16 #include<fstream>
 17 
 18 #include<string>
 19 #include<set>
 20 
 21 #define MAX 999999;
 22 
 23 
 24 using namespace std;
 25 
 26 
 27 
 28 int path[60][60];
 29 int s[60];
 30 int u[60];
 31 bool isCow[60];
 32 
 33 void dijkstra();
 34 int extract_min(int*);
 35 void relax(int);
 36 bool isEmpty();
 37 int main()
 38 
 39 {
 40 
 41     ifstream fin("comehome.in");
 42 
 43     ofstream fout("comehome.out");
 44 
 45     int num;
 46     char ch1,ch2;
 47     int value;
 48     fin>>num;
 49     for(int i=0;i<num;++i)
 50     {
 51         fin>>ch1>>ch2>>value;
 52 
 53         if(path[ch1<'a'?ch1-'A'+1:ch1-'a'+1+26][ch2<'a'?ch2-'A'+1:ch2-'a'+1+26]>value||path[ch1<'a'?ch1-'A'+1:ch1-'a'+1+26][ch2<'a'?ch2-'A'+1:ch2-'a'+1+26]==0)
 54         {
 55 
 56         path[ch1<'a'?ch1-'A'+1:ch1-'a'+1+26][ch2<'a'?ch2-'A'+1:ch2-'a'+1+26]=value;
 57         path[ch2<'a'?ch2-'A'+1:ch2-'a'+1+26][ch1<'a'?ch1-'A'+1:ch1-'a'+1+26]=value;
 58         s[ch1<'a'?ch1-'A'+1:ch1-'a'+1+26]=MAX;
 59         s[ch2<'a'?ch2-'A'+1:ch2-'a'+1+26]=MAX;
 60         if(ch1<'a')
 61             isCow[ch1-'A'+1]=true;
 62         if(ch2<'a')
 63             isCow[ch2-'A'+1]=true;
 64         }
 65         
 66 
 67     }    
 68     s['Z'-'A'+1]=0;
 69     dijkstra();
 70 
 71     int minindex=-1;
 72     for(int i=1;i<=25;i++)
 73     {
 74         if(isCow[i]&&minindex==-1)
 75             minindex=i;
 76         else if(isCow[i]&&u[i]<u[minindex])
 77             minindex=i;
 78     }
 79 
 80     fout<<static_cast<char>(minindex+'A'-1)<<" "<<u[minindex]<<endl;
 81 
 82 
 83     
 84     
 85 
 86     return 0;
 87 
 88 
 89 }
 90 void dijkstra()
 91 {
 92     int renode;
 93     while(!isEmpty())
 94     {
 95         renode=extract_min(s);
 96         if(renode==1)
 97             renode=1;
 98         relax(renode);
 99         u[renode]=s[renode];
100         s[renode]=-1;
101         if(renode==26)
102             u[renode]=-1;
103 
104     }
105 }
106 
107 bool isEmpty()
108 {
109     for(int i=1;i<=52;i++)
110     {
111         if(s[i]>0&&i!=26)
112             return false;
113     }
114     return true;
115 }
116 
117 void relax(int renode)
118 {
119     for(int i=1;i<=52;i++)
120     {
121         if(s[i]!=-1&&i!=renode&&path[renode][i]&&s[i]>s[renode]+path[renode][i])
122             s[i]=s[renode]+path[renode][i];
123     }
124 }
125 int extract_min(int*s)
126 {
127     int minindex=1;
128     for(int i=1;i<=52;i++)
129     {
130         if(i!=26&&s[i]>0)
131         {
132             if(s[minindex]==0||s[minindex]==-1)
133                 minindex=i;
134             else if(s[minindex]>s[i])
135                 minindex=i;
136             else
137                 continue;
138 
139         }
140         else if(i==26)
141         {
142             if(s[i]==0)
143                 return i;
144         }
145     }
146 
147     return minindex;
148 }

 贴个别人的...

 1  
 2 #include <algorithm>
 3 #include <climits>
 4 #include <cstdio>
 5 using namespace std;
 6  
 7 bool flag[52] = {};
 8 int a[52][52], dist[52];
 9  
10 int main()
11 {
12     int p;
13     freopen("comehome.in", "r", stdin);
14     freopen("comehome.out", "w", stdout);
15     for (int i = 0; i < 52; ++i)
16         fill_n(a[i], 52, INT_MAX/2);
17     for (scanf("%d", &p); p; --p)
18     {
19         char u, v;
20         int w;
21         scanf("%*c%c %c%d", &u, &v, &w);
22         u = islower(u) ? u-'a' : u-'A'+26;
23         v = islower(v) ? v-'a' : v-'A'+26;
24         if (w < a[u][v])
25             a[u][v] = w, a[v][u] = w;
26     }
27     copy(a[51], a[51]+52, dist);
28     for(;;)
29     {
30         int min_dist = INT_MAX, u;
31         for (int i = 0; i < 51; ++i)
32             if (!flag[i] && dist[i] < min_dist)
33                 min_dist = dist[i], u = i;
34         if (u >= 26) return printf("%c %d\n", u-26+'A', min_dist), 0;
35         flag[u] = true;
36         for (int i = 0; i < 51; ++i)
37             if (!flag[i] && dist[u]+a[u][i] < dist[i])
38                 dist[i] = dist[u]+a[u][i];
39     }
40 }

 

posted @ 2013-09-14 18:32  cavehubiao  阅读(240)  评论(0)  编辑  收藏  举报