POJ 3274 Gold Balanced Lineup 哈希

题目链接： http://poj.org/problem?id=3274

 1 #include <stdio.h>

 2 #include <string.h>

 3 #include <algorithm>

 4 

 5 bool feature[100001][30];

 6 int sum[100001][30], c[100001][30], n, k;

 7 const int prime = 99991;

 8 

 9 struct hash_table

10 {

11     int flag;

12     struct hash_table *next;

13 }*Hash[prime];

14 

15 int hash_insert(int key, int flag)

16 {

17     if(Hash[key] == NULL)

18     {

19         Hash[key] = new hash_table;

20         Hash[key]->flag = flag;

21         Hash[key]->next = NULL;

22         return 0;

23     }

24     struct hash_table *p = Hash[key];

25     while(p->next != NULL)

26     {

27         bool ok = 1;

28         for(int i = 0; i < k; i++)

29         {

30             if(c[p->flag][i] != c[flag][i])

31             {

32                 ok = 0;

33                 break;

34             }

35         }

36         if(ok)return flag - p->flag;

37         p = p->next;

38     }

39     for(int i = 0; i < k; i++)

40     {

41         if(c[p->flag][i] != c[flag][i])

42         {

43             p->next = new hash_table;

44             p->next->flag = flag;

45             p->next->next = NULL;

46             return 0;

47         }

48     }

49     return flag - p->flag;

50 }

51 

52 int main()

53 {

54     int x;

55     while(scanf("%d %d", &n, &k) != EOF)

56     {

57         memset(Hash, 0, sizeof(Hash));

58         for(int i = 1; i <= n; i++)

59         {

60             scanf("%d", &x);

61             for(int j = 0; j < k; j++)

62                 feature[i][j] = (x >> j) & 1;

63         }

64         memset(sum[0], 0, sizeof(sum[0]));

65         memset(feature[0], 0, sizeof(feature[0]));

66         int ans = 0;

67         hash_insert(0, 0);

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

69         {

70             int key = 0;

71             for(int j = 0; j < k; j++)

72             {

73                 sum[i][j] = sum[i-1][j] + feature[i][j];

74                 c[i][j] = sum[i][j] - sum[i][0];

75                 key += c[i][j] * j;

76             }

77             ans = std::max(ans, hash_insert(std::abs(key)%prime, i));

78         }

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

80     }

81     return 0;

82 }

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