ZOJ 3349 Special Subsequence 简单DP + 线段树

同 HDU 2836 只不过改成了求最长子串。

DP+线段树单点修改+区间查最值。

 

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <cstdlib>

 4 #include <algorithm>

 5 

 6 #define lson l, m, rt << 1

 7 #define rson m + 1, r, rt << 1 | 1

 8 

 9 using namespace std;

10 

11 const int MAXN = 100100;

12 

13 int n, d;

14 int val[MAXN];

15 int num[MAXN];

16 int dp[MAXN];

17 

18 int maxi[ MAXN << 2 ];

19 

20 void pushUp( int rt )

21 {

22     maxi[rt] = max( maxi[rt << 1], maxi[rt << 1 | 1] );

23     return;

24 }

25 

26 void Update( int L, int c, int l, int r, int rt )

27 {

28     if ( l == L && L == r )

29     {

30         maxi[rt] = c;

31         return;

32     }

33 

34     int m = ( l + r ) >> 1;

35     if ( L <= m ) Update( L, c, lson );

36     else Update( L, c, rson );

37     pushUp( rt );

38     return;

39 }

40 

41 int Query( int L, int R, int l, int r, int rt )

42 {

43     if ( L <= l && r <= R )

44         return maxi[rt];

45 

46     int m = ( l + r ) >> 1;

47 

48     int res = 0;

49     if ( L <= m ) res = max( res, Query( L, R, lson ) );

50     if ( R > m )  res = max( res, Query( L, R, rson ) );

51 

52     return res;

53 }

54 

55 int main()

56 {

57     while ( ~scanf( "%d%d", &n, &d ) )

58     {

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

60         {

61             scanf( "%d", &val[i] );

62             num[i] = val[i];

63         }

64 

65         sort( num + 1, num + 1 + n );

66         int cnt = unique( num + 1, num + n + 1 ) - num - 1;

67 

68         dp[0] = 0;

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

70         int ans = 0;

71 

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

73         {

74             int id = lower_bound( num + 1, num + cnt + 1, val[i] ) - num;

75             int left = lower_bound( num + 1, num + cnt + 1, val[i] - d ) - num;

76             int right = upper_bound( num + 1, num + cnt + 1, val[i] + d ) - num - 1;

77             dp[i] = Query( left, right, 1, n, 1 ) + 1;

78             ans = max( ans, dp[i] );

79             Update( id, dp[i], 1, n, 1 );

80         }

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

82     }

83     return 0;

84 }