UVA 11690 - Money Matters

/******************************************************************
***   Problem       :                                           ***
***   Author        : Shipu Ahamed (Psycho Timekiller)          ***
***   E-mail        : shipuahamed01@gmail.com                   ***
***   University    : BUBT,Dept. of CSE                         ***
***   Team          : BUBT_Psycho                               ***
***   My Blog       : http://shipuahamed.blogspot.com           ***
***   Facebook      : http://www.facebook.com/DeesheharaShipu   ***
******************************************************************/

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

#define pi 2*acos(0.0)
#define all(v) v.begin(),v.end()

//input
#define si(t) scanf("%d",&t)
#define sl(t) scanf("%lld",&t)
#define sf(t) scanf("%f",&t)
#define sd(t) scanf("%lf",&t)
#define sc(c) scanf("%c",&c)
#define sii(a,b) scanf("%d%d",&a,&b)
#define sll(a,b) scanf("%lld%lld",&a,&b)

//Output
#define P(a) printf("%d\n",a)
#define PL(a) printf("%lld\n",a)
#define PF(a) printf("%f\n",a)
#define PD(a) printf("%lf\n",a)
#define PS(a) printf("%s\n",a)
#define PSN(a) printf("%s ",a)
#define PN(a) printf("%d ",a)
#define PLN(a) printf("%lld ",a)
#define PFN(a) printf("%f ",a)
#define PDN(a) printf("%lf ",a)
#define PP(a,b) printf("%d %d\n",a,b)
#define PPN(a,b) printf("%d %d ",a,b)
#define PPL(a,b) printf("%lld %lld\n",a,b)
#define PPLN(a,b) printf("%lld %lld ",a,b)

#define CP(a) cout< vi;
typedef  vector vll;
typedef  vector vs;
typedef  set si;
typedef  set ss;
typedef  map mii;
typedef  map mll;
typedef  map msi;
typedef  map mci;

template string toString( T Number ){stringstream st;st << Number;return st.str();}
template  T SOD(T n) {__typeof(n) sum=0;for(__typeof(n) i=1;i*i<=n;i++)sum+=(n%i)?0:((i*i==n)?i:i+n/i);return sum;}

//For Define
#define forab(i,a,b) for(__typeof(b) i=(a);i<=(b);i++)
#define for0(i,n) forab(i,0,(n)-1)
#define for1(i,n) forab(i,1,n)
#define rforab(i,b,a) for(__typeof(b) i=(b);i>=(a);i--)
#define rfor0(i,n) rforab(i,(n)-1,0)
#define rfor1(i,n) rforab(i,n,1)
#define forstl(i,s) for(__typeof((s).end()) i=(s).begin(); i != (s).end(); i++)

//File input/output
#define input freopen("in.txt","r",stdin)
#define output freopen("out.txt","w",stdout)

//upper bound and lower bound
#define LB(a,value) (lower_bound(all(a),value)-a.begin())
#define UB(a,value) (upper_bound(all(a),value)-a.begin())

//Test Case & New line
#define Case(no) printf("Case %d: ",++no)
#define nl puts("")

int stringconvert(string s){int p; istringstream st(s); st>>p ; return p;}

ll pow(ll a,ll b, ll m) { ll res = 1; while(b) { if(b & 1) { res = ( (res % m) * (a % m) ) %m ; } a= ((a%m) * (a%m)) %m; b >>= 1; } return res; }
ll modInverse(ll a, ll m){return pow(a,m-2,m);}

////============ CONSTANT ===============////
#define mx7   10000007
#define mx6   1000006
#define mx5   100005
#define inf   1<<30                                           //infinity value
#define eps   1e-9
#define mx    (100010)
#define mod   1000000007
////=====================================////

int par[mx5],sum[mx5],a[mx5];

int Find(int n)
{
    if(par[n]==n)
        return n;
    return par[n]=Find(par[n]);
}

int Union(int a,int b)
{
    int u= Find(a);
    int v= Find(b);
    if(u!=v)
    {
        par[u]=v;
    }

}

int main()
{
    int t;
    si(t);
    while(t--)
    {
        int n,m;
        sii(n,m);

        cover(sum,0);

        for0(i,n)
        {
            si(a[i]),par[i]=i;
        }

        int x,y;
        while(m--)
        {
            sii(x,y);
            Union(x,y);
        }

        for0(i,n)
        {
            sum[ Find(i) ] += a[i];
        }

        bool f=true;
        for0(i,n)
        {
            if(sum[i] !=0)
            {
                    f=false;
                    break;
            }
        }

        if(f)
            puts("POSSIBLE");
        else
            puts("IMPOSSIBLE");


    }

    return 0;
}