Poj-3368 frequent values ***

/* 480 Ms
* Poj-3368.cpp
* Created on: 2011-10-14
*
*
* Rmq:
* 10 3
-1-1 1 1 1 3 10 10 10
2 3
1 10
5 10
0
*
* 1. value [I]: the value at the position I
* 2. For each value, record the location where the value is last, endpoint
* 3. Record the first value of each value: prepointvalue. In example, the first value of 1 is-1, that is, prepointvalue [1] =-1.
* 4. record the number of occurrences of each value, for example, frequency [1] = 4
*
* For each Q (x, y), find the number of occurrences of ANS = max {value [x]: A1, value [y]: A2, located in X, frequency between values Y and different from the values of value [X] and value [y]: A3}
* Pay attention to different situations. Some of the above three values may not be calculated, for example, Q (1, 2), A3 does not, and A1 = a2
* This should be discussed in detail
*
* In addition, if a3 is used for traversal, it can use sparse-table.
*
* Finally, because the value may be negative, maxn must be added to the most array table.
*/
# Include <cstdio>
# Include <cstring>
Using namespace STD;

Const int maxn = 100000 + 10;
Const int maxk = 20;

Int N, Q;
// As described above
Int value [maxn], endpoint [2 * maxn], frequency [2 * maxn], prepointvalue [2 * maxn];
// Used for sparse_table data
Int valuenum [2 * maxn], stfre [maxn], d [maxn] [maxk], num;

Inline int max (int lhs, int RHs ){
Return (stfre [LHS]> stfre [RHS]? LHS: RHs );
}

// St preprocessing
Void Prest (){
For (INT I = 0; I <num; I ++)
D [I] [0] = I;

For (Int J = 1; (1 <j) <= num; j ++)
For (INT I = 0; I + (1 <j)-1 <num; I ++)
D [I] [J] = max (d [I] [J-1], d [I + (1 <(J-1)] [J-1]);
}

// St
Int sparsetable (int x, int y ){
Int K;
For (k = 1; (1 <k) <= (Y-x + 1); k ++ );
K --;

If (stfre [d [x] [k] <stfre [d [Y-(1 <k) + 1] [k])
Return stfre [d [Y-(1 <k) + 1] [k];
Else
Return stfre [d [x] [k];
}



Int main (){
While (scanf ("% d", & N )){
If (n = 0) return 0;

Memset (frequency, 0, sizeof (frequency ));
Num = 0;

Scanf ("% d", & Q );

// Input
// The first value
Scanf ("% d", & value [0]);
Frequency [maxn + value [0] ++;
Valuenum [maxn + value [0] = num ++;

// 1-N value
For (INT I = 1; I <n; I ++ ){
Scanf ("% d", & value [I]);
// Enter a new value
If (frequency [maxn + value [I] = 0 ){
// Record the data of the previous value
Endpoint [maxn + value [I-1] = I-1;
Stfre [valuenum [maxn + value [I-1] = frequency [maxn + value [I-1];

// Record the data about the current new value
Prepointvalue [maxn + value [I] = value [I-1];
Valuenum [maxn + value [I] = num ++;
}
Frequency [maxn + value [I] ++;
}
// Record the last worthwhile data
Endpoint [maxn + value [n-1] = n-1;
Stfre [valuenum [maxn + value [n-1] = frequency [maxn + value [n-1];


// Rmq
Prest ();

Int X, Y;
For (INT I = 0; I <q; I ++ ){
Scanf ("% d", & X, & Y );

X --; y --; // note that the array starts from 0.
Int tmpmax =-1;
// Case 1
If (value [x] = value [y]) tmpmax = Y-x + 1;
// Other cases: for example, Q (1, 2)
Else {
Int xx = valuenum [maxn + value [endpoint [maxn + value [x] + 1];
Int YY = valuenum [maxn + prepointvalue [maxn + value [y];
// Case 2: for example, Q (1, 7) or Q (1, 10) // YY <XX such as Q (1, 3)
If (yy> = XX ){
Tmpmax = sparsetable (XX, YY );
}
// A1
Int xfre = endpoint [maxn + value [x]-x + 1;
// A2
Int yfre = Y-endpoint [maxn + prepointvalue [maxn + value [y];

If (xfre> tmpmax) tmpmax = xfre;
If (yfre> tmpmax) tmpmax = yfre;
}

Printf ("% d \ n", tmpmax );
}
}



Return 0;
}