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divde the 12 balls into 3 sets of 4.
+ j  G2 T7 a& D" g/ A/ n! d- Etvb now,tvbnow,bttvbweight any 2 sets.
5 v5 P2 R& L9 g2 |8 B3 nTVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。if the 2 sets are equal, then you know the heavy one is in the third
2 d+ `4 O! {& M- ~' I' t5 [& @, Utvb now,tvbnow,bttvbif one of the 2 is heavier, then the heavy one is in that set5.39.217.76  W) m2 h+ v, o& \& ?7 i) d: r% X
then divide the 4 balls into 2.
" c) H( I: O( l2 ~! h- e9 Iweigh them5.39.217.765 w! F& ~6 ?1 z5 C
and divide the heavier into 1
0 V4 Q5 _2 D! Q) D: Q8 uand weight them.
* E* b2 F8 Q5 b8 k8 ], i( J5.39.217.763 x weighing and get the ans.  
9 l/ S( h5 \  h9 g, Bin less than 15 secs.