poj3411Paid Roads(dfs)

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想偷点懒用矩阵存 一直WA 后来看讨论说有重边改为邻接表 这题边可能走了不止一次 我设的最多两次可过

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<stdlib.h>

 6 using namespace std;

 7 #define INF 0xfffffff

 8 struct node

 9 {

10     int u,v,w1,w2,d,next;

11 }ed[22];

12 int head[12];

13 int n,m,p[12][12],ans;

14 int vis[12],t;

15 void init()

16 {

17     t = 0;

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

19 }

20 void add(int u,int v,int w1,int w2,int d)

21 {

22     ed[t].u = u;

23     ed[t].v = v;

24     ed[t].w1 = w1;

25     ed[t].w2 = w2;

26     ed[t].d = d;

27     ed[t].next = head[u];

28     head[u] = t++;

29 }

30 void dfs(int u,int sum)

31 {

32     int i,s=sum;

33     if(sum>ans)

34     return ;

35     if(u==n)

36     {

37         ans = sum;

38         return ;

39     }

40     for(i = head[u] ; i!= -1; i = ed[i].next)

41     {

42         int v = ed[i].v;

43         int tt = vis[v];

44         if(p[u][v]<3)

45         {

46             vis[v] = 1;

47             p[u][v]++;

48             if(ed[i].d==u||ed[i].d==i||vis[ed[i].d])

49             {

50                 sum+=min(ed[i].w1,ed[i].w2);

51             }

52             else

53             {

54                 sum+=ed[i].w2;

55             }

56             dfs(v,sum);

57             sum = s;

58             p[u][v]--;

59             vis[v] = tt;

60         }

61     }

62 }

63 int main()

64 {

65     int a,b,c,pp,r;

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

67     {

68         init();

69         memset(vis,0,sizeof(vis));

70         memset(p,0,sizeof(p));

71         ans = INF;

72         while(m--)

73         {

74             scanf("%d%d%d%d%d",&a,&b,&c,&pp,&r);

75             add(a,b,pp,r,c);

76         }

77         vis[1] = 1;

78         dfs(1,0);

79         if(ans!=INF)

80         printf("%d\n",ans);

81         else

82         puts("impossible");

83     }

84     return 0;

85 }

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