POJ 1734 Sightseeing trip(无向图最小环+输出路径)

题目链接

 1 #include <cstdio>

 2 #include <string>

 3 #include <cstring>

 4 #include <queue>

 5 #include <map>

 6 #include <algorithm>

 7 using namespace std;

 8 #define LL __int64

 9 #define MOD 1000000007

10 #define INF 0xffffff

11 int dp[101][101],g[101][101],pre[101][101];

12 int ans[1001];

13 int main()

14 {

15     int n,m,minz,i,j,k,sv,ev,w,num,temp;

16     while(scanf("%d%d",&n,&m)!=EOF)

17     {

18         memset(pre,-1,sizeof(pre));

19         for(i = 1; i <= n; i ++)

20         {

21             for(j = 1; j <= n; j ++)

22                 dp[i][j] = g[i][j] = INF;

23             dp[i][i] = g[i][i] = 0;

24         }

25         for(i = 1; i <= m; i ++)

26         {

27             scanf("%d%d%d",&sv,&ev,&w);

28             g[sv][ev] = dp[sv][ev] = min(dp[sv][ev],w);

29             g[ev][sv] = dp[ev][sv] = min(dp[ev][sv],w);

30             pre[sv][ev] = ev;

31             pre[ev][sv] = sv;

32         }

33         minz = INF;

34         for(i = 1; i <= n; i ++)//求最小环

35         {

36             for(j = 1; j <= i-1; j ++)

37                 for(k = j+1; k <= i-1; k ++)

38                 {

39                     if(minz > dp[j][k] + g[j][i] + g[i][k])

40                     {

41                         minz = dp[j][k] + g[j][i] + g[i][k];

42                         num = 1;

43                         ans[0] = i;

44                         temp = j;

45                         while(temp != -1)

46                         {

47                             ans[num++] = temp;

48                             temp = pre[temp][k];

49                         }

50                     }

51                 }

52             for(j = 1; j <= n; j ++)

53                 for(k = 1; k <= n; k ++)

54                 {

55                     if(dp[j][k] > dp[j][i] + dp[i][k])

56                     {

57                         dp[j][k] = dp[j][i] + dp[i][k];

58                         pre[j][k] = pre[j][i];

59                     }

60                 }

61         }

62         if(minz == INF)

63         printf("No solution.\n");

64         else

65         {

66             for(i = 0;i < num;i ++)

67             {

68                 if(i == 0)

69                 printf("%d",ans[i]);

70                 else

71                 printf(" %d",ans[i]);

72             }

73         }

74         printf("\n");

75     }

76     return 0;

77 }