Solution doubledummy problem 3

http://doubledummy.net/Problem0003.html
  take the K spade from south lead a dia from southCASE 1: west does not play the king In this case north plays small and south wins this trickThen north takes the ace of dia in the next trick, then takes two spade tricks and gives a spade trick to east.the east, at this point has only hearts, so, the east is forced to give one heart trick to north, then north gets two more spade tricks and two club tricks in south to complete the required 10!
CASE 2: west plays the king on the dia leadthen, take the trick with the ace from north

  then pick the two spade tricks from north and give a spade trick to east

  discard all your diamonds from south on these spade trickseast's hand is H AQ98765, D 8

  South is C AKJ98765

 North is S 32, H KJ10, D 32, C 2

  we come to west's hand in a little while CASE 2 a): east takes the diamond trick and then the ace of heart and then leads heart

  in this case north takes two heart tricks, two spade tricks, and gives south two club tricks to finish with the required 10

 CASE 2 b): east takes the diamond trick and then gives a heart to northnow, North takes two spade tricks

 at this point north has two hearts, a diamond and a club

  south has 4 clubs

  now, consider west's hand

 if west has at most 2 clubs, then north leads a club and takes all 4 tricks down south (we need only 3)

  if west has no diamond, then north takes a diamond trick and then gives the lead to south to cash the two club tricks

 so, west must have at least 1 diamond and at least 3 club, which means all hearts have been discarded

  this is good news because now, west cannot lead the hand back to east's heart ace

  in this case north gives a diamond to west

 and then west is forced to give 3 club tricks to south

CASE 2 c): east gives a heart trick to north

11:12 PM north in this case returns the diamond trick to south, and then we are back to either case 1, or case 2

  CASE 2 d): east takes the ace of heart and then gives a heart trick

  in this case north picks two heart tricks

11:13 PM then two spade tricks

  and two club tricks

  to finish with the required 10