10344 - 23 out of 5

10344 - 23 out of 5.cpp

/**
 * Tittle:	10344 - 23 out of 5
 * Author:	Cheng-Shih, Wong
 * Date:	2015/07/04
 */

// include files
#include <bits/stdc++.h>

using namespace std;

// definitions
#define FOR(i,a,b) for( int i=(a),_n=(b); i<=_n; ++i )
#define clr(x,v) memset( x, v, sizeof(x) )

typedef vector<int> VI;

// declarations
int num[5];
VI seq;
bool vis[5];

// functions
bool input( void )
{
	FOR( i, 0, 4 ) scanf( "%d", &num[i] );
	
	FOR( i, 0, 4 ) 
		if( num[i] != 0 ) return true;
	return false;
}

bool check( int l, int res )
{
	if( l == 5 ) {
		return res==23;
	}

	if( check(l+1,res+seq[l]) ) return true;
	if( check(l+1,res-seq[l]) ) return true;
	if( check(l+1,res*seq[l]) ) return true;
	return false;
}

bool mkSeq( int l )
{
	if( l == 5 ) {
		return check( 1, seq[0] );
	}

	FOR( i, 0, 4 ) if( !vis[i] ) {
		vis[i] = true;
		seq.push_back( num[i] );
		if( mkSeq(l+1) ) return true;
		seq.pop_back();
		vis[i] = false;
	}

	return false;
}

void solve( void )
{
	clr( vis, false );
	seq.clear();
	puts( mkSeq(0) ? "Possible":"Impossible" );
}

// main function
int main( void )
{

	// input
	while( input() ) {
		solve();
	}
	
	return 0;
}