hdu 1044

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1044

思路：看网上大牛们的做法都是bfs+dfs,弱菜表示不会啊，然后觉得bfs也应该不会超时吧，就搞了一把，orz...890ms险过。

 1 #include<iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<queue>

 5 using namespace std;

 6 #define MAXN 52

 7 struct Node{

 8     int x,y,time;

 9     int value,key;

10 };

11 char map[MAXN][MAXN];

12 bool mark[MAXN][MAXN][1212];

13 int value[MAXN];

14 int n,m,t,l,ans;

15 int dir[4][2]={{-1,0},{1,0},{0,-1},{0,1}};

16 Node st,ed;

17 bool flag;

18 

19 void bfs(){

20     memset(mark,false,sizeof(mark));

21     queue<Node>Q;

22     Node p,q;

23     Q.push(st);

24     while(!Q.empty()){

25         p=Q.front();

26         Q.pop();

27         if(p.time>t)continue;

28         if(p.x==ed.x&&p.y==ed.y&&p.time<=t){

29             ans=max(ans,p.value);

30             flag=true;

31         }

32         for(int i=0;i<=4;i++){

33             q.x=p.x+dir[i][0];

34             q.y=p.y+dir[i][1];

35             q.key=p.key;

36             q.value=p.value;

37             q.time=p.time;

38             if(q.x<1||q.x>n||q.y<1||q.y>m||map[q.x][q.y]=='*')continue;

39             if(map[q.x][q.y]>='A'&&map[q.x][q.y]<='J'){

40                 int x=map[q.x][q.y]-'A';

41                 int y=value[x];

42                 if(q.key&(1<<x)){

43                     q.time+=1;

44                     if(!mark[q.x][q.y][q.key]){ mark[q.x][q.y][q.key]=true;Q.push(q); }

45                 }else {

46                     q.key+=(1<<x);

47                     q.value+=value[x+1];

48                     q.time+=1;

49                     if(!mark[q.x][q.y][q.key]){ mark[q.x][q.y][q.key]=true;Q.push(q); }

50                 }

51             }else if(!mark[q.x][q.y][q.key]){

52                 mark[q.x][q.y][q.key]=true;

53                 q.time+=1;

54                 Q.push(q);

55             }

56         }

57     }

58 }

59 

60 

61 int main(){

62     int _case,x=1;

63     scanf("%d",&_case);

64     while(_case--){

65         if(x>1)puts("");

66         scanf("%d%d%d%d",&m,&n,&t,&l);

67         for(int i=1;i<=l;i++)scanf("%d",&value[i]);

68         for(int i=1;i<=n;i++){

69             scanf("%s",map[i]+1);

70             for(int j=1;j<=m;j++){

71                 if(map[i][j]=='@'){ st.x=i,st.y=j,st.time=0,st.key=0,st.value=0; }

72                 else if(map[i][j]=='<'){ ed.x=i,ed.y=j,ed.time=t,ed.key=0,ed.value=0; }

73             }

74         }

75         ans=0,flag=false;

76         bfs();

77         printf("Case %d:\n",x++);

78         if(flag){

79             printf("The best score is %d.\n",ans);

80         }else

81             puts("Impossible");

82     }

83     return 0;

84 }

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