UVa 10276 Hanoi Tower Troubles Again!

UVa 10276 Hanoi Tower Troubles Again!

此题使用了交表。打表的做法参见本博客的另一篇文章《网络流24题》。
以下是我的代码：

#include < cstdio >
#include < cstring >
#include < cmath >
using   namespace  std;

const   int  kMaxn( 1350 );
const   int  kMaxm( 1000007 );

struct  Edge
{
     int  u,v;
};

int  ans,nx,ny;
int  cnt,first[kMaxn],next[kMaxm];
Edge e[kMaxm];
int  maxmatch,cx[kMaxn],cy[kMaxn];
int  distx[kMaxn],disty[kMaxn];
int  head,tail,q[kMaxn];

void  Clear()
{
    cnt = 0 ;
     for ( int  i = 1 ;i <= ans;i ++ )
        first[i] =- 1 ;
}

void  AddEdge( int  u, int  v)
{
    cnt ++ ;
    e[cnt].u = u;
    e[cnt].v = v;
    next[cnt] = first[u];
    first[u] = cnt;
}

bool  OK( int  a, int  b)
{
     return  (( int )sqrt(( double )a + b)) * (( int )sqrt(( double )a + b)) == a + b;
}

void  Build()
{
    nx = ny = ans;
     for ( int  i = 1 ;i <= ans;i ++ )
         for ( int  j = i + 1 ;j <= ans;j ++ )
             if (OK(i,j))
                AddEdge(i,j);
}

bool  BFS()
{
     bool  re( false );
    head = tail = 0 ;
    memset(distx, 0 , sizeof (distx));
    memset(disty, 0 , sizeof (disty));
     for ( int  i = 1 ;i <= nx;i ++ )
         if (cx[i] ==- 1 )
            q[tail ++ ] = i;
     while (head != tail)
    {
         int  h,t;
         for (h = head,t = tail;h != t;h = (h + 1 ) % kMaxn)
        {
             int  u(q[h]);
             for ( int  i = first[u];i !=- 1 ;i = next[i])
            {
                 int  v(e[i].v);
                 if ( ! disty[v])
                {
                    disty[v] = distx[u] + 1 ;
                     if (cy[v] ==- 1 )
                        re = true ;
                     else
                    {
                        distx[cy[v]] = disty[v] + 1 ;
                        q[tail] = cy[v];
                        tail = (tail + 1 ) % kMaxn;
                    }
                }
            }
        }
        head = t;
    }
     return  re;
}

bool  DFS( int  u)
{
     for ( int  i = first[u];i !=- 1 ;i = next[i])
    {
         int  v(e[i].v);
         if (disty[v] == distx[u] + 1 )
        {
            disty[v] = 0 ;
             if (cy[v] ==- 1   ||  DFS(cy[v]))
            {
                cx[u] = v;
                cy[v] = u;
                 return   true ;
            }
        }
    }
     return   false ;
}

void  HopcroftKarp()
{
    maxmatch = 0 ;
    memset(cx, - 1 , sizeof (cx));
    memset(cy, - 1 , sizeof (cy));
    
     while (BFS())
         for ( int  i = 1 ;i <= nx;i ++ )
             if (cx[i] ==- 1   &&  DFS(i))
                maxmatch ++ ;
}

int  Solve()
{
    Clear();
    Build();
    HopcroftKarp();
     return  ans - maxmatch;
}

int  r[ 57 ];

void  Init()
{
    memset(r, - 1 , sizeof (r));
     for (ans = 1 ;r[ 50 ] ==- 1 ;ans ++ )
    {
         int  t(Solve());
         if (t >= 1   &&  r[t - 1 ] ==- 1 )
        {
            r[t - 1 ] = ans - 1 ;
            printf( " %d\n " ,r[t - 1 ]);
        }
    }
}

int  main()
{
    freopen( " data.in " , " r " ,stdin);
    freopen( " data.out " , " w " ,stdout);
    
    Init();
    
     int  T;
    scanf( " %d " , & T);
     while (T -- )
    {
         int  n;
        scanf( " %d " , & n);
        
        printf( " %d\n " ,r[n]);
    }
}