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  • STL--H

    H - Black Box
    Time Limit:1000MS     Memory Limit:10000KB     64bit IO Format:%I64d & %I64u
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    Description

    Our Black Box represents a primitive database. It can save an integer array and has a special i variable. At the initial moment Black Box is empty and i equals 0. This Black Box processes a sequence of commands (transactions). There are two types of transactions: 

    ADD (x): put element x into Black Box; 
    GET: increase i by 1 and give an i-minimum out of all integers containing in the Black Box. Keep in mind that i-minimum is a number located at i-th place after Black Box elements sorting by non- descending. 

    Let us examine a possible sequence of 11 transactions: 

    Example 1 
    N Transaction i Black Box contents after transaction Answer 
          (elements are arranged by non-descending)   
    
    1 ADD(3)      0 3 
    2 GET         1 3                                    3 
    3 ADD(1)      1 1, 3 
    4 GET         2 1, 3                                 3 
    5 ADD(-4)     2 -4, 1, 3 
    6 ADD(2)      2 -4, 1, 2, 3 
    7 ADD(8)      2 -4, 1, 2, 3, 8 
    8 ADD(-1000)  2 -1000, -4, 1, 2, 3, 8 
    9 GET         3 -1000, -4, 1, 2, 3, 8                1 
    10 GET        4 -1000, -4, 1, 2, 3, 8                2 
    11 ADD(2)     4 -1000, -4, 1, 2, 2, 3, 8   

    It is required to work out an efficient algorithm which treats a given sequence of transactions. The maximum number of ADD and GET transactions: 30000 of each type. 


    Let us describe the sequence of transactions by two integer arrays: 


    1. A(1), A(2), ..., A(M): a sequence of elements which are being included into Black Box. A values are integers not exceeding 2 000 000 000 by their absolute value, M <= 30000. For the Example we have A=(3, 1, -4, 2, 8, -1000, 2). 

    2. u(1), u(2), ..., u(N): a sequence setting a number of elements which are being included into Black Box at the moment of first, second, ... and N-transaction GET. For the Example we have u=(1, 2, 6, 6). 

    The Black Box algorithm supposes that natural number sequence u(1), u(2), ..., u(N) is sorted in non-descending order, N <= M and for each p (1 <= p <= N) an inequality p <= u(p) <= M is valid. It follows from the fact that for the p-element of our u sequence we perform a GET transaction giving p-minimum number from our A(1), A(2), ..., A(u(p)) sequence. 


    Input

    Input contains (in given order): M, N, A(1), A(2), ..., A(M), u(1), u(2), ..., u(N). All numbers are divided by spaces and (or) carriage return characters.

    Output

    Write to the output Black Box answers sequence for a given sequence of transactions, one number each line.

    Sample Input

    7 4
    3 1 -4 2 8 -1000 2
    1 2 6 6

    Sample Output

    3
    3
    1
    2
    题意非常麻烦:解释一下数据 7 4 表示给出7个数,有4个询问,下一行给出7个数,在下一行有4个询问,“1”代表从头到第一个元素中最小的值。“2”代表从头到第二个元素中第二小的值。“6”代表从头到第六个元素中第三小的值,“6”代表从头到第六个元素中第四小的值。给出的询问中 a[i] <= a[j] (i < j) ;

    做法,定义两个优先队列。以大优先的p1。以小优先的p2,假设要求的是第x小的值。p1中存下(x-1)个小值,那么第x个就是p2的队首,在求第一个小的值,p1为空,求完第一个小的值后,将p2的队首放入p1,再来求第二小的值。读取给出的数(a)时,假设a大于p1的队首,那么a放入p2。否则。将a放入p1,p1的队首放入p2,保证p1的个数均比p2小。且为(x-1)个,读取完数后p2的队首就是第x小的数,输出。再把p2的队首放入p1,运行之前的操作,得到下一个要求的最小值。

    用两个优先队列。分开总体的数组,得到第x小值


    #include <cstdio>
    #include <cstring>
    #include <queue>
    #include <vector>
    #include <algorithm>
    using namespace std;
    #define LL __int64
    priority_queue <LL> p1 ;
    priority_queue <LL,vector<LL>,greater<LL> > p2 ;
    LL a[6000000] ;
    int main()
    {
        int i , j , n , m , x ;
        LL temp ;
        while(scanf("%d %d", &n, &m)!=EOF)
        {
            while( !p1.empty() )
                p1.pop();
            while( !p2.empty() )
                p2.pop() ;
            for(i = 1 ; i <= n ; i++)
                scanf("%I64d", &a[i]);
            i = 1 ;
            while(m--)
            {
                scanf("%d", &x);
                for( ; i <= x ; i++)
                {
                    if( p1.empty() || p1.top() < a[i] )
                        p2.push(a[i]);
                    else
                    {
                        p1.push(a[i]);
                        temp = p1.top() ;
                        p1.pop() ;
                        p2.push(temp);
                    }
                }
                temp = p2.top();
                p2.pop() ;
                printf("%d
    ", temp);
                p1.push(temp);
            }
        }
        return 0;
    }
    




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  • 原文地址:https://www.cnblogs.com/wgwyanfs/p/7095558.html
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