• Codeforces 460 D. Little Victor and Set



    暴力+构造


    If r - l ≤ 4 we can all subsets of size not greater than k. Else, if k = 1, obviously that answer is l. If k = 2, answer is 1, because xor of numbers 2x and 2x + 1 equls 1. If k ≥ 4 answer is 0 because xor of to pairs with xor 1 is 0.

    If k = 3, we can choose numbers 2x and 2x + 1 with xor 1. So we need to know, if we can get xor equals 0. Suppose that there are 3 such numbers xy and z (r ≥ x > y > z ≥ l) with xor equals 0. Consider the most non-zero bit of numberx. At the same bit of y it's also 1, because xor equls 0, and y > z. Consider the next bit of numbers. If z have 0 there, we have to do next: set the previous bit of numbers x and y equals 0, and set current bit equals 1. Obviously xor still equals 0, z hadn't changed and numbers x and y stood closer to z, so they are still at [l, r].And x > y.Consider the next bit of numbers. If z has zero here than we will change most bits of x и y at the same way and so on. z > 0, so somewhen we will get to bit in which z has 1. Since xorequals 0, the same bit of x would be 1 because x > y, and y would have 0 there. At the next bits we will change bit in x to 0, and in numbers y and z to 1.Finally z would be greater or equal than before, and x would be less or greater than before, and x > y > z would be correct. So, we have the next: if such numbers xy and z exist than also exist numbers:

    1100…000

    1011…111

    0111…111

    with xor equals 0. There are not much such triples, so we can check them.


    D. Little Victor and Set
    time limit per test
    1 second
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Little Victor adores the sets theory. Let us remind you that a set is a group of numbers where all numbers are pairwise distinct. Today Victor wants to find a set of integers S that has the following properties:

    • for all x  the following inequality holds l ≤ x ≤ r;
    • 1 ≤ |S| ≤ k;
    • lets denote the i-th element of the set S as si; value  must be as small as possible.

    Help Victor find the described set.

    Input

    The first line contains three space-separated integers l, r, k (1 ≤ l ≤ r ≤ 1012; 1 ≤ k ≤ min(106, r - l + 1)).

    Output

    Print the minimum possible value of f(S). Then print the cardinality of set |S|. Then print the elements of the set in any order.

    If there are multiple optimal sets, you can print any of them.

    Sample test(s)
    input
    8 15 3
    
    output
    1
    2
    10 11
    
    input
    8 30 7
    
    output
    0
    5
    14 9 28 11 16
    
    Note

    Operation  represents the operation of bitwise exclusive OR. In other words, it is the XOR operation.





    #include <iostream>
    #include <cstdio>
    #include <cstring>
    #include <algorithm>
    
    using namespace std;
    
    typedef long long int LL;
    
    LL L,R,K;
    LL ans=0x3f3f3f3f3f3f3f3f;
    
    int main()
    {
        cin>>L>>R>>K;
        if(R-L+1<=4)
        {
            LL m=R-L+1;
            LL sig=0;
            for(LL i=1;i<(1LL<<m);i++)
            {
                LL temp=0;
                LL wei=0;
                LL si=i;
                while(si)
                {
                    wei++;
                    si=si&(si-1);
                }
                if(wei>K) continue;
                for(LL j=0;j<m;j++)
                {
                    if(i&(1LL<<j))
                    {
                        temp^=L+j;
                    }
                }
                if(temp<ans)
                {
                    ans=temp;
                    sig=i;
                }
            }
            cout<<ans<<endl;
            LL wei=0;
            LL tsig=sig;
            while(tsig)
            {
                wei++;
                tsig=tsig&(tsig-1);
            }
            cout<<wei<<endl;
            for(LL i=0;i<m;i++)
            {
                if(sig&(1<<i))
                {
                    cout<<L+i<<" ";
                }
            }
            cout<<endl;
        }
        else
        {
            if(K==1)
            {
                cout<<L<<endl;
                cout<<1<<endl;
                cout<<L<<endl;
            }
            else if(K==2)
            {
                if(L%2) L++;
                cout<<1<<endl;
                cout<<2<<endl;
                cout<<L<<" "<<L+1<<endl;
            }
            else if(K==3)
            {
                bool flag=false;
    
                LL mx=3,mi=1;
                while(mx<=R)
                {
                    if(mi>=L)
                    {
                        flag=true;
                        cout<<0<<endl<<3<<endl;
                        cout<<mx<<" "<<mx-1<<" "<<mi<<endl;
                        break;
                    }
    
                    mx<<=1LL;
                    mi<<=1LL; mi++;
                }
    
                if(flag==false)
                {
                    if(L%2) L++;
                    cout<<1<<endl;
                    cout<<2<<endl;
                    cout<<L<<" "<<L+1<<endl;
                }
            }
            else
            {
                cout<<0<<endl;
                cout<<4<<endl;
                if(L%2) L++;
                cout<<L<<" "<<L+1<<" "<<L+2<<" "<<L+3<<endl;
            }
        }
        return 0;
    }
    


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  • 原文地址:https://www.cnblogs.com/blfbuaa/p/6760104.html
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