Missionaries-Cannibal Problem

# include <iostream>
# include <cstdio>
# include <set>
# include <queue>

using namespace std;

# define FOR(C, F, L) for ( int C = F; C <= L; C++ )
# define MP(X,Y) make_pair((X),(Y))


typedef pair<int, int> pi;
typedef pair<pi, pi>ppii;
typedef pair<pi,int> ppi;
queue < ppii > Q;
int C, M, R, level=0;
set <pair<pi,int> > S;

int elementFound ( ppi node)
{
    set < ppi > :: iterator it;
    it = S.find(node);
    if ( it == S.end() )return 0;
    else return 1;
}

void generatecases ( ppii X )
{
    int x = X.first.first;
    int y = X.first.second;
    int b = X.second.first;
    int dist = X.second.second;
    if (b)
        {
        b += 1; b %= 2;
        FOR(I,0,R)
        FOR(J,0,R)
            {
            if (!(I+J));
            else {
                if ( (y-J>=0) && (I+J <=R))
                if ((x-I==0) || (x-I==M) ||
                     ((x-I==y-J) &&(M-(x-I) == C-(y-J)&&(x-I>=0))))
                    {
                    ppi temp = MP(MP(x-I,y-J),b);
                    if ( !elementFound(temp))
                        {
                        Q.push(MP(MP(x-I,y-J),MP(b,dist+1)));
                        S.insert(temp);
                        }
                    }
                }
            }
        }
    else {
        b += 1; b %= 2;
        FOR(I,0,R)
        FOR(J,0,R)
            {
            if (!(I+J));
            else {
                if ((y+J<=C) && (I+J<=R))
                if ((x+I==M) || (x+I== 0) ||
                     (x+I==y+J && M-(x+I)==C-(y+J)&&(x+I<=M)) )
                    {
                    ppi temp = MP(MP(x+I,y+J),b);
                    if ( !elementFound(temp) )
                        {
                        Q.push(MP(MP(x+I,y+J),MP(b, dist+1)));
                        S.insert( temp );
                        }
                    }
                }
            }
        }
}

int main()
{
    int t;cin >> t;
    FOR(U,1,t){
    scanf("%d%d%d",&M,&C,&R);
    while(!Q.empty())Q.pop();
    S.erase(S.begin(),S.end());
    Q.push(MP(MP(M,C),MP(1,0)));
    S.insert(MP(MP(M,C),1));
    int flag=1;
    while (!Q.empty())
    {
        ppii top = Q.front();
        Q.pop();
        if (top.first.first==0 && top.first.second==0)
            {
            cout << top.second.second <<endl;flag=0;break;
            }
        else generatecases(top);
    }
    if(flag){
    int impossible = -1;
    cout << impossible<<endl;}
}
    return 0;
}