ural 1045. A funny game

ural 1045. A funny game

treedp:

#include < iostream >
using   namespace  std;

int  N,k;
int  chd[ 2100 ],pre[ 2100 ],now[ 1100 ];
bool  f[ 1010 ];
bool  vis[ 1010 ];
int  ans;
void  treedp( int  x){
    vis[x] = 1 ;
     while (now[x] > 0 ){
         if ( ! vis[chd[now[x]]]){
            treedp(chd[now[x]]);
             if ( ! f[chd[now[x]]]){
                f[x] = 1 ;
                 if (x == k){
                     if (ans > chd[now[x]])
                        ans = chd[now[x]];
                }
                 else   return ;
            }
        }
        now[x] = pre[now[x]];
    }
}
int  main()
{
    scanf( " %d%d " , & N, & k);
     int  c = 0 ,x,y;
    memset(now, 0 , sizeof (now));
     for ( int  i = 1 ;i < N; ++ i){
        scanf( " %d%d " , & x, & y);
        c ++ ; pre[c] = now[x]; chd[c] = y; now[x] = c;
        c ++ ; pre[c] = now[y]; chd[c] = x; now[y] = c;
    }
    memset(vis, 0 , sizeof (vis));
    memset(f, 0 , sizeof (f));
    ans = 0xFFFFFFF ;
    treedp(k);
     if ( ! f[k]) printf( " First player loses\n " );
     else  printf( " First player wins flying to airport %d\n " ,ans);
     return   0 ;
}

非递归：

#include < iostream >
using   namespace  std;

struct  arr{
     int  win,used;
}f[ 1001 ];
int  N,k;
int  g[ 1001 ][ 1001 ] = { 0 };
int  dis[ 1001 ] = { 0 };
int  deg[ 1001 ] = { 0 };
void  input()
{
    scanf( " %d%d " , & N, & k);
     int  x,y;
     for ( int  i = 1 ;i < N; ++ i){
        scanf( " %d%d " , & x, & y);
        g[x][y] = g[y][x] = 1 ;
        deg[x] ++ ; deg[y] ++ ;
    }
     for ( int  i = 1 ;i <= N; ++ i)
         if (deg[i] == 1 && i != k){
            f[i].used = 1 ; f[i].win = 0 ;
        }
         else  f[i].used = f[i].win = 0 ;
}
void  bfs(){
     int  que[ 10001 ],h,t;
     int  vis[ 1001 ] = { 0 };
    h = t = 1 ;
    que[ 1 ] = k; vis[k] = 1 ;
     while (h <= t){
         int  x = que[h];
         for ( int  y = 1 ;y <= N; ++ y)
             if (g[x][y] &&! vis[y]){
                t ++ ;
                que[t] = y;
                vis[y] = 1 ;
                dis[y] = dis[x] + 1 ;
            }
        h ++ ;
    }
}
void  dp()
{
     int  link[ 1001 ] = { 0 };
     int  cur[ 10001 ] = { 0 };
     int  top = 1 ;
     int  ret =- 1 ;
    link[ 1 ] = k;
     do {
         if (ret == 0 )
            f[link[top]].win = 1 ;
        cur[top] ++ ;
         while ((g[link[top]][cur[top]] == 0 || dis[cur[top]] != dis[link[top]] + 1 ) && cur[top] <= N)
            cur[top] ++ ;
         if (cur[top] > N || f[link[top]].used == 1 ){
            f[link[top]].used = 1 ;
            ret = f[link[top]].win;
            cur[top] = 0 ;
             -- top;
        }
         else {
             ++ top;
            ret =- 1 ;
            link[top] = cur[top - 1 ];
        }
    } while (top);
}
int  main()
{
    freopen( " funnyg.in " , " r " ,stdin);
    freopen( " funnyg.out " , " w " ,stdout);
    input();
    bfs();
    dp();
     if (f[k].win == 0 )
        printf( " First player loses\n " );
     else {
         for ( int  i = 1 ;i <= N; ++ i)
             if (dis[i] == 1 && f[i].win == 0 ){
                printf( " First player wins flying to airport %d\n " ,i);
                 break ;
            }
    }
     return   0 ;
}