【HDU】5757ProductBo【分情况讨论+队列】

题目链接：Product Bo

思想很好，挺有趣的题，在床上突然会做的。

#include 
using namespace std ;

typedef long long LL ;
typedef pair <int , int > pii ;

#define clr( a , x ) memset ( a , x , sizeof a )

const int MAXN = 200005 ;

struct Node {
    LL val ;
    int l1 , m1 , r1 ;
    int l2 , m2 , r2 ;
    int f ;
    Node () {}
    Node ( LL v , int l1 , int m1 , int r1 , int l2 , int m2 , int r2 )
        : val ( v ) , l1 ( l1 ) , m1 ( m1 ) , r1 ( r1 ) , l2 ( l2 ) , m2 ( m2 ) , r2 ( r2 ) , f ( 0 ) {}
} ;

queue  q ;
int n , m , k ;
int pos[MAXN] , c1 ;
int neg[MAXN] , c2 ;
LL sum1[MAXN] , sum2[MAXN] ;

int check ( int n , int m , int k ) {
    if ( n - m <m ) m = n - m ;
    LL ans = 1 ;
    for ( int i = 1 ; i <= m ; ++ i ) {
        ans *= n ;
        ans /= i ;
        if ( ans >= k ) return -1 ;
        -- n ;
    }
    if ( ans >= k ) return -1 ;
    return ans ;
}

int check2 ( int c1 , int c2 , int m , int k ) {
    int ans = 0 ;
    for ( int i = 0 ; i <= c2 && i <= m ; i += 2 ) if ( m - i <= c1 ) {
        int x1 = check ( c1 , m - i , k ) , x2 = check ( c2 , i , k ) ;
        if ( x1 == -1 || x2 == -1 || 1LL * x1 * x2 >= k ) return -1 ;
        ans += x1 * x2 ;
        if ( ans >= k ) return -1 ;
    }
    return ans ;
}

int cal ( int c1 , int c2 , int m , int k ) {
    int ans = 0 ;
    for ( int i = 1 ; i <= c2 && i <= m ; ++ i ) if ( m - i <= c1 ) {
        int x1 = check ( c1 , m - i , k ) , x2 = check ( c2 , i , k ) ;
        if ( x1 == -1 || x2 == -1 || 1LL * x1 * x2 >= k ) return -1 ;
        ans += x1 * x2 ;
        if ( ans >= k ) return -1 ;
    }
    return ans ;
}

int cmp ( const int& a , const int& b ) {
    return a > b ;
}

void solve () {
    c1 = c2 = 0 ;
    for ( int i = 1 ; i <= n ; ++ i ) {
        char op[2] ;
        int x ;
        scanf ( "%s" , op ) ;
        if ( op[0] == '+' ) {
            scanf ( "%d" , &x ) ;
            pos[++ c1] = x ;
        }
        if ( op[0] == '-' ) {
            scanf ( "%d" , &x ) ;
            neg[++ c2] = x ;
        }
    }
    //printf ( "%d %d\n" , c1 , c2 ) ;
    int tot = check2 ( c1 , c2 , m , k ) ;
    //printf ( "%d\n" , tot ) ;
    if ( tot == -1 ) {
        sort ( pos + 1 , pos + c1 + 1 , cmp ) ;
        sort ( neg + 1 , neg + c2 + 1 , cmp ) ;
        sum1[0] = sum2[0] = 0 ;
        for ( int i = 1 ; i <= c1 ; ++ i ) {
            sum1[i] = sum1[i - 1] + pos[i] ;
        }
        for ( int i = 1 ; i <= c2 ; ++ i ) {
            sum2[i] = sum2[i - 1] + neg[i] ;
        }
        int cnt = 0 ;
        LL l = -1e15 , r = 1e15 ;
        while ( l             LL lim = l + r + 1 >> 1 ;
            cnt = 0 ;
            while ( !q.empty () ) q.pop () ;
            for ( int i = 0 ; i <= c2 && i <= m ; i += 2 ) {
                if ( m - i <= c1 ) {
                    if ( sum2[i] + sum1[m - i] >= lim ) {
                        q.push ( Node ( sum2[i] + sum1[m - i] , m - i - 1 , m - i , c1 + 1 , i - 1 , i , c2 + 1 ) ) ;
                    }
                }
            }
            while ( !q.empty () ) {
                Node u = q.front () , tmp ;
                q.pop () ;
                ++ cnt ;
                if ( cnt >= k ) break ;
                if ( !u.f && u.m1 ) {
                    if ( u.m1 + 1                         tmp = u ;
                        tmp.val = u.val - pos[u.m1] + pos[u.m1 + 1] ;
                        tmp.m1 = u.m1 + 1 ;
                        if ( tmp.val >= lim ) q.push ( tmp ) ;
                    }
                    if ( u.l1 && u.l1 + 1                         tmp = u ;
                        tmp.val = u.val - pos[u.l1] + pos[u.l1 + 1] ;
                        tmp.l1 = u.l1 - 1 ;
                        tmp.m1 = u.l1 + 1 ;
                        tmp.r1 = u.m1 ;
                        if ( tmp.val >= lim ) q.push ( tmp ) ;
                    }
                }
                if ( u.m2 ) {
                    if ( u.m2 + 1                         tmp = u ;
                        tmp.val = u.val - neg[u.m2] + neg[u.m2 + 1] ;
                        tmp.m2 = u.m2 + 1 ;
                        tmp.f = 1 ;
                        if ( tmp.val >= lim ) q.push ( tmp ) ;
                    }
                    if ( u.l2 && u.l2 + 1                         tmp = u ;
                        tmp.val = u.val - neg[u.l2] + neg[u.l2 + 1] ;
                        tmp.l2 = u.l2 - 1 ;
                        tmp.m2 = u.l2 + 1 ;
                        tmp.r2 = u.m2 ;
                        tmp.f = 1 ;
                        if ( tmp.val >= lim ) q.push ( tmp ) ;
                    }
                }
            }
            if ( cnt 1 ;
            else l = lim ;
        }
        printf ( "+ %I64d\n" , l ) ;
        return ;
    }
    int zero = cal ( c1 + c2 , n - c1 - c2 , m , k ) ;
    if ( zero == -1 || tot + zero >= k ) {
        printf ( "0\n" ) ;
        return ;
    }
    tot += zero ;
    k -= tot ;
    sort ( pos + 1 , pos + c1 + 1 ) ;
    sort ( neg + 1 , neg + c2 + 1 ) ;
    sum1[0] = sum2[0] = 0 ;
    for ( int i = 1 ; i <= c1 ; ++ i ) {
        sum1[i] = sum1[i - 1] + pos[i] ;
    }
    for ( int i = 1 ; i <= c2 ; ++ i ) {
        sum2[i] = sum2[i - 1] + neg[i] ;
    }
    int cnt = 0 ;
    LL l = -1e15 , r = 1e15 ;
    while ( l         LL lim = l + r >> 1 ;
        cnt = 0 ;
        while ( !q.empty () ) q.pop () ;
        for ( int i = 1 ; i <= c2 && i <= m ; i += 2 ) {
            if ( m - i <= c1 ) {
                if ( sum2[i] + sum1[m - i] <= lim ) q.push ( Node ( sum2[i] + sum1[m - i] , m - i - 1 , m - i , c1 + 1 , i - 1 , i , c2 + 1 ) ) ;
            }
        }
        while ( !q.empty () ) {
            Node u = q.front () , tmp ;
            q.pop () ;
            //printf ( "%d: %I64d %d %d\n" , cnt + 1 , u.val , u.m1 , u.m2 ) ;
            ++ cnt ;
            if ( cnt >= k ) break ;
            if ( !u.f && u.m1 ) {
                if ( u.m1 + 1                     tmp = u ;
                    tmp.val = u.val - pos[u.m1] + pos[u.m1 + 1] ;
                    tmp.m1 = u.m1 + 1 ;
                    if ( tmp.val <= lim ) q.push ( tmp ) ;
                }
                if ( u.l1 && u.l1 + 1                     tmp = u ;
                    tmp.val = u.val - pos[u.l1] + pos[u.l1 + 1] ;
                    tmp.l1 = u.l1 - 1 ;
                    tmp.m1 = u.l1 + 1 ;
                    tmp.r1 = u.m1 ;
                    if ( tmp.val <= lim ) q.push ( tmp ) ;
                }
            }
            if ( u.m2 ) {
                if ( u.m2 + 1                     tmp = u ;
                    tmp.val = u.val - neg[u.m2] + neg[u.m2 + 1] ;
                    tmp.m2 = u.m2 + 1 ;
                    tmp.f = 1 ;
                    if ( tmp.val <= lim ) q.push ( tmp ) ;
                }
                if ( u.l2 && u.l2 + 1                     tmp = u ;
                    tmp.val = u.val - neg[u.l2] + neg[u.l2 + 1] ;
                    tmp.l2 = u.l2 - 1 ;
                    tmp.m2 = u.l2 + 1 ;
                    tmp.r2 = u.m2 ;
                    tmp.f = 1 ;
                    if ( tmp.val <= lim ) q.push ( tmp ) ;
                }
            }
        }
        //printf ( "%d %I64d %I64d\n" , cnt , l , r ) ;
        if ( cnt 1 ;
        else r = lim ;
    }
    printf ( "- %I64d\n" , l ) ;
}

int main () {
    while ( ~scanf ( "%d%d%d" , &n , &m , &k ) && ( n || m || k ) ) solve () ;
    return 0 ;
}