HDU 4618 Palindrome Sub-Array(DP)

题目链接

我还是图样啊....比赛的时候没敢暴力去搜...

 1 #include <cstdio>

 2 #include <cstdlib>

 3 #include <cstring>

 4 #include <map>

 5 #include <ctime>

 6 #include <cmath>

 7 using namespace std;

 8 #define LL __int64

 9 char dp[301][301][301];

10 int p[301][301];

11 int n,m;

12 int dfs(int x,int y,int step)

13 {

14     int i,j,k;

15     if(step == 1)

16     return 1;

17     else if(step == 0)

18     return 1;

19     if(x > n||y > m)

20     return 2;

21     if(dp[x][y][step] == 1)

22     return 1;

23     else if(dp[x][y][step] == 2)

24     return 2;

25     int flag = 1;

26     for(i = x,j = x+step-1,k = 1;k <= step/2&&flag;i ++,j --,k ++)

27     {

28         if(p[i][y] == p[j][y]&&p[i][y] == p[i][y+step-1])

29         ;

30         else

31         flag = 0;

32     }

33     for(i = y,j = y+step-1,k = 1;k <= step/2&&flag;i ++,j --,k ++)

34     {

35         if(p[x][i] == p[x][j]&&p[x][i] == p[x+step-1][i])

36         ;

37         else

38         flag = 0;

39     }

40     if(flag == 0)

41     {

42         dp[x][y][step] = 2;

43         return 2;

44     }

45     else if(flag)

46     {

47         return dp[x+1][y+1][step-2] = dfs(x+1,y+1,step-2);

48     }

49     return 0;

50 }

51 int main()

52 {

53     int t,i,j,k,flag;

54     scanf("%d",&t);

55     while(t--)

56     {

57         scanf("%d%d",&n,&m);

58         memset(dp,0,sizeof(dp));

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

60         {

61             for(j = 1;j <= m;j ++)

62             {

63                 scanf("%d",&p[i][j]);

64             }

65         }

66         flag = 1;

67         for(i = min(n,m);i >= 2&&flag;i --)

68         {

69             for(j = 1;j <= n-i+1&&flag;j ++)

70             {

71                 for(k = 1;k <= m-i+1&&flag;k ++)

72                 {

73                     if(dfs(j,k,i) == 1)

74                     flag = 0;

75                 }

76             }

77             if(!flag) break;

78         }

79         printf("%d\n",i);

80     }

81     return 0;

82 }