/* mollykez.tc - lrb - 11/24/08

psq int n [ /* if n is m*m for some m returns n else returns 0
  int m,w;for (m=1;;++m) [
    w=m*m;if (w>n) return 0
    if (w==n) return w
    ]
  return 0
]

mollykez [ /* determine dance partners 
  int cnt,k,m,d,o,dl,du
  int table(1100)
  char hi,lo,blue,white;hi='1';lo='0';blue='4';white='7'
  hilo hi;color blue;cls;posc(2,1)
  pl"mollykez.tc - lrb - 11/24/08";hilo lo
  pl"";pl"lower? ";dl=gn;ps"upper? ";du=gn;pl""
  for (d=dl;d<=du;d=d+2) [
    for (k=1;k<=d;++k) table(k)=0 
    cnt=0;for (k=(d/2+1);k<=d;++k) [
      if (!table(k)) [
        for (m=1;m<(d/2+1);++m) [
          if (psq(k+m)*(!table(m))) [
            table(k)=m;table(m)=k;++cnt;break
            ] /* if
          ] /* m loop
        ] /* if 
      ] /* k loop
    if (cnt==d/2) [
      pl"";pl"";pn d;ps" dancers";pl"";pl""
      for (k=1;k<=d/2;++k) [
        pn k;ps" -";pn table(k);ps" ("
        pn k+table(k);ps" )";pl""
        ] /* k loop
      sak;pl""
      ] /* if 
    else pn d
    ] /* d loop 
  pl""  
]