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。

 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <algorithm>

 #define lson l, m, rt << 1
 #define rson m + 1, r, rt << 1 | 1

 using namespace std;

 const int MAXN = ;

 int n, d;
 int val[MAXN];
 int num[MAXN];
 int dp[MAXN];

 int maxi[ MAXN <<  ];

 void pushUp( int rt )
 {
     maxi[rt] = max( maxi[rt << ], maxi[rt <<  | ] );
     return;
 }

 void Update( int L, int c, int l, int r, int rt )
 {
     if ( l == L && L == r )
     {
         maxi[rt] = c;
         return;
     }

     int m = ( l + r ) >> ;
     if ( L <= m ) Update( L, c, lson );
     else Update( L, c, rson );
     pushUp( rt );
     return;
 }

 int Query( int L, int R, int l, int r, int rt )
 {
     if ( L <= l && r <= R )
         return maxi[rt];

     int m = ( l + r ) >> ;

     int res = ;
     if ( L <= m ) res = max( res, Query( L, R, lson ) );
     if ( R > m )  res = max( res, Query( L, R, rson ) );

     return res;
 }

 int main()
 {
     while ( ~scanf( "%d%d", &n, &d ) )
     {
         for ( int i = ; i <= n; ++i )
         {
             scanf( "%d", &val[i] );
             num[i] = val[i];
         }

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

         dp[] = ;
         memset( maxi, , sizeof(maxi) );
         int ans = ;

         for ( int i = ; i <= n; ++i )
         {
             int id = lower_bound( num + , num + cnt + , val[i] ) - num;
             int left = lower_bound( num + , num + cnt + , val[i] - d ) - num;
             int right = upper_bound( num + , num + cnt + , val[i] + d ) - num - ;
             dp[i] = Query( left, right, , n,  ) + ;
             ans = max( ans, dp[i] );
             Update( id, dp[i], , n,  );
         }
         printf( "%d\n", ans );
     }
     return ;
 }