题解 | 继续xxx定律

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    while(cin >> n)
    {
        if(n == 0) return 0;
        vector<int> a(n);
        for(int i = 0; i < n; i++) cin >> a[i];
        vector<int> core(1001);
        for(int i = 0; i < n; i++)
        {
            int x = a[i];
            if(core[x] != - 1)
            {
                if(x <= 1000) core[x] = 1;
                while(x != 1)
                {
                    if(x % 2 == 1)
                    {
                        x = (3 * x + 1) / 2;
                        if(x <= 1000) core[x] = -1;
                    }
                    else 
                    {
                        x = x / 2;
                        if(x <= 1000) core[x] = -1;
                    }
                }
            }
        }
        for(int i = n - 1; i >= 0; i--)
        {
            if(core[a[i]] == 1) cout << a[i] << " ";
        }                
    }
    return 0;
}