On the first sight i thought i'd need O(3 ^ 16) but the problem is much easier.

print "IMPOSSIBLE" instead of "Impossible"

if your store data in array of pairs begin loop from zero i=0 not from 1!

//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("avx")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

#define re return
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define sqrt(x) sqrt(abs(x))
#define mp make_pair
#define pi (3.14159265358979323846264338327950288419716939937510)
#define fo(i, n) for(int i = 0; i < n; ++i)
#define ro(i, n) for(int i = n - 1; i >= 0; --i)
#define unique(v) v.resize(unique(all(v)) - v.begin())

template <class T> T abs (T x) { re x > 0 ? x : -x; }
template <class T> T sqr (T x) { re x * x; }
template <class T> T gcd (T a, T b) { re a ? gcd (b % a, a) : b; }
template <class T> int sgn (T x) { re x > 0 ? 1 : (x < 0 ? -1 : 0); }

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<string> vs;
typedef double D;
typedef long double ld;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef unsigned long long ull;
typedef tree <pair<int, char>, null_type, less<pair<int, char>>, rb_tree_tag, tree_order_statistics_node_update> _tree;

const int maxn = 20;
int n;
string s[20][3];
int p[maxn];
vector <string> ans;
bool was[maxn][3];

bool f (int pos, int last = -1) {
    if (pos == n) re true;
    if (pos && was[pos][last]) re false;
    if (pos) was[pos][last] = true;
    if (pos) {
        fo(i, 3) {
            if (s[p[pos - 1]][last] < s[p[pos]][i] && f(pos + 1, i)) {
                ans.pb(s[p[pos]][i]);
                re true;
            }
        }
    } else {
        fo(i, 3) {
            if (f(pos + 1, i)) {
                ans.pb(s[p[pos]][i]);
                re true;
            }
        }
    }
    re false;
}

int main() {
    cin >> n;
    fo(i, n) fo(j, 3) cin >> s[i][j];
    fo(i, n) cin >> p[i], p[i]--;
    if (f(0)) {
        reverse(all(ans));
        for (string &s : ans) cout << s << '\n';
    } else cout << "IMPOSSIBLE\n";
    re 0;
}

What is test #25?

Уважаемые администраторы сайта!

Подскажите, пожалуйста, что Вы собираетесь делать с посылками, которые получали AC на компиляторе Intel C++ 7, и получают Time Limit на компиляторах G++ 4.7.2 и Visual C++ 2010?

У меня, например, около 4-5 таких задач было, пришлось все их перерешивать по-другому.
Ведь теперь нет возможности отправить задачу на старом компиляторе.

Извиняйте, но тогда нужно перетестировать посылки под Intel C++ 7 на новых компиляторах, а то результаты и рейтинг получаются НЕЧЕСТНЫМИ !!! Ведь не все перерешивают уже "сданные" задачи.

In JAVA version of the tests, in test 3, N<3, be careful when declaring array sizes.
In C# version of the tests there is no such test.

Who can give me some tests?

What is test #20?

what is test 30?

#include<iostream>
#include<string>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
int main()
{
int b[26],n,i,j;bool t=true;
string a[26][3],str,s[26];
cin>>n;
for(i=0;i<n;i++)
                {
                cin>>a[i][0];
                cin>>a[i][1];
                cin>>a[i][2];
                if(a[i][1]>a[i][2])
                                   {
                                   str=a[i][1];
                                   a[i][1]=a[i][2];
                                   a[i][2]=str;
                                   }


                if(a[i][0]>a[i][1])
                                   {
                                   str=a[i][0];
                                   a[i][0]=a[i][1];
                                   a[i][1]=str;
                                   }


                }
   /*
for(i=0;i<n;i++)
{for(j=0;j<3;j++)
 cout<<a[i][j]<<" ";
 cout<<endl;
}   */
    for(i=0;i<n;i++)
                    {
                    cin>>b[i];
                    if(i==0)
                    s[i]=a[b[i]-1][0];
                    else{j=0;
                         while(a[b[i]-1][j]<=s[i-1]&&j<3)
                                       {


                                       j++;}
                         if(a[b[i]-1][j]>s[b[i]-1])
                         s[i]=a[b[i]-1][j];
                         else t=false;
                         }

                    }
                 if(t)
    for(i=0;i<n;i++)
    cout<<s[i]<<endl;
    else cout<<"IMPOSSIBLE";

system("pause");
}

Instead of
shaitan
volume
watchmen


Shooting
Size
Watchmen

I sort all variants for each problem in lexicographic order. First I output first variant for first problem. Next I compare last outputted word and first variant fo next problem, if it is not satisfies I compare last output and second word etc. If all variants are incorrect I print "IMPOSSIBLE". Last I print words in founded order. Where is my mistake?
Sorry for my English.

String comparison:
s1="aa";
s2="aaa";

s1<s2==true;
s2>s1==false;

Could you say what's in test #7? It files but can't see any errors in my solution :(

My program passed all tests from forum. I sorted with c++ string comparision operator '<', and wrote my own function. But, anyway WA #25? Why???

please, help me...
my code:

#include <iostream>

using namespace std;



int main()
{
    int n,m[16],k;
    char c[48][20],v[16][20],ch[3][20];
    cin>>n;
    for(int i=0;i<n*3;i++)
        cin>>c[i];
    for(int i=0;i<n;i++)
    {
        cin>>k;
        m[i]=k;
    }
    k=(m[0]-1)*3;
    if((strcmp(c[k],c[k+1])<=0)&&(strcmp(c[k],c[k+2])<=0)){strcpy(v[0],c[k]);}
    if((strcmp(c[k+1],c[k])<=0)&&(strcmp(c[k+1],c[k+2])<=0)){strcpy(v[0],c[k+1]);}
    if((strcmp(c[k+1],c[k])<=0)&&(strcmp(c[k+1],c[k+2])<=0)){strcpy(v[0],c[k+1]);}
    for(int i=1;i<n;i++)
    {
        k=(m[i]-1)*3;
        if((strcmp(c[k],c[k+1])<=0)&&(strcmp(c[k],c[k+2])<=0))
        {
            strcpy(ch[0],c[k]);
            if(strcmp(c[k+1],c[k+2])<=0)
            {
                strcpy(ch[1],c[k+1]);
                strcpy(ch[2],c[k+2]);
            }
            else
            {
                strcpy(ch[2],c[k+1]);
                strcpy(ch[1],c[k+2]);
            }
        }

            if((strcmp(c[k+1],c[k])<=0)&&(strcmp(c[k+1],c[k+2])<=0))
            {
                strcpy(ch[0],c[k+1]);
                if(strcmp(c[k],c[k+2])<=0)
                {
                    strcpy(ch[1],c[k]);
                    strcpy(ch[2],c[k+2]);
                }
                else
                {
                    strcpy(ch[2],c[k]);
                    strcpy(ch[1],c[k+2]);
                }
            }

                if((strcmp(c[k+2],c[k])<=0)&&(strcmp(c[k+2],c[k+1])<=0))
                {
                    strcpy(ch[0],c[k+2]);
                    if(strcmp(c[k],c[k+1])<=0)
                    {
                        strcpy(ch[1],c[k]);
                        strcpy(ch[2],c[k+1]);
                    }
                    else
                    {
                        strcpy(ch[2],c[k]);
                        strcpy(ch[1],c[k+1]);
                    }
                }

        if(strcmp(v[i-1],ch[0])<=0)
        {
            strcpy(v[i],ch[0]);
        }
        else
        {
            if(strcmp(v[i-1],ch[1])<=0)
            {
                strcpy(v[i],ch[1]);
            }
            else
            {
                if(strcmp(v[i-1],ch[2])<=0)
                {
                    strcpy(v[i],ch[2]);
                }
                else
                {
                    cout<<"IMPOSSIBLE";
                    return 0;
                }
            }
        }

    }
    for(int i=0;i<n;i++)
    {
        cout<<v[i]<<endl;
    }
    return 0;
}

why my answer of the test#1 is incorrect?
codenames
grille
keywords
mnemonic
playgame
random
rectangle
rejudge
shaitan
size
twosides

Give it me, please :(