uva1620 Lazy Susan

留坑(p.256)

什么找规律啊 坑爹

 #include<cstdio>
 #include<cstring>
 #include<cstdlib>
 #include<algorithm>
 #include<iostream>

 using namespace std;

 void setIO(const string& s) {
     freopen((s + ".in").c_str(), "r", stdin);
     freopen((s + ".out").c_str(), "w", stdout);
 }
 template<typename Q> Q read(Q& x) {
     static char c, f;
     for(f = ; c = getchar(), !isdigit(c); ) if(c == '-') f = ;
     for(x = ; isdigit(c); c = getchar()) x = x *  + c - '';
     if(f) x = -x;
     return x;
 }
 template<typename Q> Q read() {
     static Q x; read(x); return x;
 }

 const int N =  + ;

 int a[N];

 int main() {
 #ifdef DEBUG
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w", stdout);
 #endif

     int T(read<int>());
     while(T--) {
         int n(read<int>()), cnt();
         for(int i = ; i < n; i++) {
             read(a[i]);
             for(int j = ; j < i; j++) cnt ^= a[i] < a[j];
         }
         if((~n & ) || !cnt) puts("possible");
         else puts("impossible");
     }

     return ;
 }