hdu 3530 Subsequence(单调队列)

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std ;

const int maxn = 111111 ;
int n , m , num[maxn] , k ;
struct Deque {
	int val[2][maxn], pos[2][maxn];
	int star[2] , tail[2] ;
	void init () {
		star[0] = 1 ;
		tail[0] = 0 ;
		star[1] = 1 ;
		tail[1] = 0 ;
	}
	int judge (int c, int v) {
		return c ^ (val[c][tail[c]] < v);
	}
	void push (int id, int v) {
		int i ;
	//	printf ( "id = %d , v = %d\n" , id , v ) ;
		for ( i = 0 ; i < 2 ; i ++ ) {
			while ( star[i] <= tail[i] && judge ( i , v ) )
				tail[i] -- ;
			val[i][++tail[i]] = v ;
			pos[i][tail[i]] = id ;
		}
	}
	void pop ( int c ) {
		if ( star[c] <= tail[c] ) star[c] ++ ;
	}
	int gao ( int &last ) {
		while ( (val[0][star[0]] - val[1][star[1]] > k ) ) {
			if ( pos[1][star[1]] < pos[0][star[0]] ) {
				last = pos[1][star[1]] ;
				pop ( 1 ) ;
			}
			else {
				last = pos[0][star[0]] ;
				pop ( 0 ) ;
			}
		}
		if ( val[0][star[0]] - val[1][star[1]] < m ) return -1 ;
		return last ;
	}
} q ;

int main () {
	int i , j ;
	while ( scanf ( "%d%d%d" , &n , &m , &k ) != EOF ) {
	    for ( i = 1 ; i <= n ; i ++ )
            scanf ( "%d" , &num[i] ) ;
        q.init () ;
        int ans = 0 , last = 0 ;
        for ( i = 1 ; i <= n ; i ++ ) {
            q.push ( i , num[i] ) ;
            int k = q.gao ( last ) ;
            if ( k == -1 ) continue ;
            last = k ;
            ans = max ( ans , i - last ) ;
        }
        printf ( "%d\n" , ans ) ;
	}
	return 0 ;
}