Problem 019 —— UVa 1587 - Box

Ivan works at a factory that produces heavy machinery. He hasa simple job -- he knocks up wooden boxes of different sizesto pack machinery for delivery to the customers. Each boxis a rectangular parallelepiped. Ivan uses six rectangular wooden palletsto
make a box. Each pallet is used for one side of the box.



Joe delivers pallets for Ivan. Joe is not very smart andoften makes mistakes -- he brings Ivan pallets that do not fittogether to make a box. But Joe does not trust Ivan. It alwaystakes a lot of time to explain Joe that he has made a mistake.Fortunately, Joe
adores everything related to computers and sincerelybelieves that computers never make mistakes. Ivan has decided touse this for his own advantage. Ivan asks you to writea program that given sizes of six rectangular palletstells whether it is possible to make
a box out of them.

Input

Input file contains several test cases. Each of them consists of six lines. Each line describes one pallet andcontains two integer numbersw and
h (1

w,h

10 000)
--width and height of the pallet in millimeters respectively.

Output

For each test case, print one output line. Write a single word `POSSIBLE' to the output file if it is possibleto make a box using six given pallets for its sides. Write a single word`IMPOSSIBLE' if it is not possible to do so.

Sample Input

1345 2584
2584 683
2584 1345
683 1345
683 1345
2584 683
1234 4567
1234 4567
4567 4321
4322 4567
4321 1234
4321 1234

Sample Output

POSSIBLE
IMPOSSIBLE

#include"cstdio"
#include"iostream"
#include"cstring"
#include"cstdlib"
#include <algorithm>
using namespace std;

int box[6][2];
int x[3][2];
int pd[6];

int main()
{
    while(cin >> box[0][0] >> box[0][1]){
        for(int i=1;i<6;i++)
            cin >> box[i][0] >> box[i][1];
        for(int i=0;i<6;i++){
            if(box[i][0]>box[i][1]){
                int t=box[i][0];
                box[i][0]=box[i][1];
                box[i][1]=t;
            }
        }
        int k=0;
        memset(x,0,sizeof(x));
        for(int i=0;i<5;i++)
            for(int j=i+1;j<6;j++){
                if(box[i][0]==box[j][0]&&box[i][1]==box[j][1]&&box[i][0]){
                    x[k][0]=box[i][0],x[k++][1]=box[i][1];
                    box[j][0]=box[j][1]=box[i][1]=box[i][0]=0;
                }
            }
        k=0;
        memset(pd,0,sizeof(pd));
        for(int i=0;i<3;i++)
            for(int j=0;j<2;j++)
                pd[k++]=x[i][j];
        sort(pd,pd+6);
        if(pd[0]==0)
            printf("IMPOSSIBLE\n");
        else if(pd[0]==pd[1]&&pd[2]==pd[3]&&pd[4]==pd[5])
            printf("POSSIBLE\n");
        else
            printf("IMPOSSIBLE\n");
        memset(box,0,sizeof(box));
    }
    return 0;
}