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  • Codeforces 892 D.Gluttony

    D. Gluttony
    time limit per test
    2 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    You are given an array a with n distinct integers. Construct an array b by permuting a such that for every non-empty subset of indices S = {x1, x2, ..., xk} (1 ≤ xi ≤ n0 < k < n) the sums of elements on that positions in a and b are different, i. e.

    Input

    The first line contains one integer n (1 ≤ n ≤ 22) — the size of the array.

    The second line contains n space-separated distinct integers a1, a2, ..., an (0 ≤ ai ≤ 109) — the elements of the array.

    Output

    If there is no such array b, print -1.

    Otherwise in the only line print n space-separated integers b1, b2, ..., bn. Note that b must be a permutation of a.

    If there are multiple answers, print any of them.

    Examples
    input
    2
    1 2
    output
    2 1 
    input
    4
    1000 100 10 1
    output
    100 1 1000 10
    Note

    An array x is a permutation of y, if we can shuffle elements of y such that it will coincide with x.

    Note that the empty subset and the subset containing all indices are not counted.

    题目大意:给定一个数组a,将a中的元素调换位置变成b数组,使得对于每一个下标子集,a中对应下标的元素和不等于b中对应下标的元素和.

    分析:构造题.如果第i位的数是第j大的,那么就把第j+1大的放在第i位,如果已经是最大的了,就把最小的放在第i位,这样一定是对的.证明的话就是看是否选最大的那个数.

          这个数据范围真的是让人分分钟想到状压......

    #include <cstdio>
    #include <cmath>
    #include <queue>
    #include <cstring>
    #include <iostream>
    #include <algorithm>
    
    using namespace std;
    
    int n, a[30];
    
    struct node
    {
        int x, id;
    }e[30];
    
    bool cmp(node a, node b)
    {
        return a.x < b.x;
    }
    
    int main()
    {
        scanf("%d", &n);
        for (int i = 1; i <= n; i++)
        {
            scanf("%d", &e[i].x);
            e[i].id = i;
        }
        sort(e + 1, e + 1 + n, cmp);
        for (int i = 1; i <= n; i++)
            a[e[i].id] = i;
        for (int i = 1; i <= n; i++)
        {
            int t = (a[i] + 1) % n;
            if (t == 0)
                t = n;
            printf("%d ", e[t].x);
        }
    
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/zbtrs/p/7858386.html
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