211 lines
5.9 KiB
Plaintext
211 lines
5.9 KiB
Plaintext
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C fortran version of proving you can't win at tic-tac-toe if the opponent is competent
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C constants:
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C score win: 6
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C score tie: 5
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C score lose: 4
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C score max: 9
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C score min: 2
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C piece X: 1
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C piece O: 2
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C piece blank: 0
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program ttt
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integer*4 moves
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integer*2 b(9), sp(10), sv(10), sa(10), sb(10), sm(10)
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integer*2 mc, l
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integer*2 alpha, beta, wi, st, sc, v, p, pm, m
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common /area/ b,sp,sv,sa,sb,sm,mc,alpha,beta,wi,st,sc,v,p,pm,m
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integer*2 system
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do 6 l = 1, 9, 1
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b( l ) = 0
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6 continue
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moves = 0
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do 10 l = 1, 10, 1
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C do 10 l = 1, 1, 1
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mc = 0
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m = 1
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call runmm
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m = 2
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call runmm
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m = 5
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call runmm
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moves = moves + mc
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10 continue
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write( *, 20 ) moves
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20 format( ' moves: ', I6 )
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end
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1000 subroutine runmm
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integer*2 b(9), sp(10), sv(10), sa(10), sb(10), sm(10)
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integer*2 mc, l
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integer*2 alpha, beta, wi, st, sc, v, p, pm, m
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common /area/ b,sp,sv,sa,sb,sm,mc,alpha,beta,wi,st,sc,v,p,pm,m
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alpha = 2
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beta = 9
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p = m
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b(m) = 1
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call minmax
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b(m) = 0
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return
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end
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2000 subroutine winner
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integer*2 b(9), sp(10), sv(10), sa(10), sb(10), sm(10)
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integer*2 mc, l
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integer*2 alpha, beta, wi, st, sc, v, p, pm, m
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common /area/ b,sp,sv,sa,sb,sm,mc,alpha,beta,wi,st,sc,v,p,pm,m
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wi = b( 1 )
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if ( 0 .eq. wi ) go to 2100
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if ( ( wi .eq. b( 2 ) ) .and. ( wi .eq. b( 3 ) ) ) return
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if ( ( wi .eq. b( 4 ) ) .and. ( wi .eq. b( 7 ) ) ) return
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2100 wi = b( 4 )
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if ( 0 .eq. wi ) go to 2200
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if ( ( wi .eq. b( 5 ) ) .and. ( wi .eq. b( 6 ) ) ) return
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2200 wi = b( 7 )
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if ( 0 .eq. wi ) go to 2300
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if ( ( wi .eq. b( 8 ) ) .and. ( wi .eq. b( 9 ) ) ) return
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2300 wi = b( 2 )
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if ( 0 .eq. wi ) go to 2400
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if ( ( wi .eq. b( 5 ) ) .and. ( wi .eq. b( 8 ) ) ) return
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2400 wi = b( 3 )
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if ( 0 .eq. wi ) go to 2500
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if ( ( wi .eq. b( 6 ) ) .and. ( wi .eq. b( 9 ) ) ) return
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2500 wi = b( 5 )
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if ( 0 .eq. wi ) return
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if ( ( wi .eq. b( 1 ) ) .and. ( wi .eq. b( 9 ) ) ) return
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if ( ( wi .eq. b( 3 ) ) .and. ( wi .eq. b( 7 ) ) ) return
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wi = 0
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end
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4000 subroutine minmax
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integer*2 b(9), sp(10), sv(10), sa(10), sb(10), sm(10)
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integer*2 mc, l
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integer*2 alpha, beta, wi, st, sc, v, p, pm, m
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common /area/ b,sp,sv,sa,sb,sm,mc,alpha,beta,wi,st,sc,v,p,pm,m
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st = 0
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v = 0
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4100 mc = mc + 1
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if ( st .lt. 4 ) go to 4150
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C the computed goto is about 20% faster than calling winner
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C call winner
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go to ( 5010, 5020, 5030, 5040, 5050, 5060, 5070, 5080, 5090 ), p
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4110 if ( wi .eq. 0 ) go to 4140
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if ( wi .ne. 1 ) go to 4130
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sc = 6
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go to 4280
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4130 sc = 4
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go to 4280
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4140 if ( st .ne. 8 ) go to 4150
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sc = 5
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go to 4280
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4150 if ( b( p ) .eq. 1 ) go to 4160
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v = 2
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pm = 1
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go to 4170
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4160 v = 9
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pm = 2
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4170 p = 1
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4180 if ( b( p ) .ne. 0 ) go to 4500
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b( p ) = pm
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4182 st = st + 1
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sp( st ) = p
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sv( st ) = v
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sa( st ) = alpha
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sb( st ) = beta
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sm( st ) = pm
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go to 4100
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4280 p = sp( st )
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v = sv( st )
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alpha = sa( st )
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beta = sb( st )
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pm = sm( st )
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st = st - 1
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b( p ) = 0
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if ( pm .eq. 1 ) go to 4340
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if ( sc .eq. 4 ) go to 4530
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if ( sc .lt. v ) v = sc
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if ( v .lt. beta ) beta = v
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if ( beta .le. alpha ) go to 4520
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go to 4500
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4340 if ( sc .eq. 6 ) go to 4530
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if ( sc .gt. v ) v = sc
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if ( v .gt. alpha ) alpha = v
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if ( alpha .ge. beta ) go to 4520
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4500 p = p + 1
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if ( p .lt. 10 ) go to 4180
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4520 sc = v
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4530 if ( st .eq. 0 ) return
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go to 4280
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5010 wi = b(1)
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if ( ( wi .eq. b(2) ) .and. ( wi .eq. b(3) ) ) goto 4110
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if ( ( wi .eq. b(4) ) .and. ( wi .eq. b(7) ) ) goto 4110
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if ( ( wi .eq. b(5) ) .and. ( wi .eq. b(9) ) ) goto 4110
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wi = 0
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go to 4110
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5020 wi = b(2)
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(3) ) ) goto 4110
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if ( ( wi .eq. b(5) ) .and. ( wi .eq. b(8) ) ) goto 4110
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wi = 0
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go to 4110
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5030 wi = b(3)
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(2) ) ) goto 4110
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if ( ( wi .eq. b(6) ) .and. ( wi .eq. b(9) ) ) goto 4110
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if ( ( wi .eq. b(5) ) .and. ( wi .eq. b(7) ) ) goto 4110
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wi = 0
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go to 4110
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5040 wi = b(4)
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if ( ( wi .eq. b(5) ) .and. ( wi .eq. b(6) ) ) goto 4110
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(7) ) ) goto 4110
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wi = 0
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go to 4110
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5050 wi = b(5)
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(9) ) ) goto 4110
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if ( ( wi .eq. b(3) ) .and. ( wi .eq. b(7) ) ) goto 4110
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if ( ( wi .eq. b(2) ) .and. ( wi .eq. b(8) ) ) goto 4110
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if ( ( wi .eq. b(4) ) .and. ( wi .eq. b(6) ) ) goto 4110
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wi = 0
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go to 4110
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5060 wi = b(6)
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if ( ( wi .eq. b(4) ) .and. ( wi .eq. b(5) ) ) goto 4110
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if ( ( wi .eq. b(3) ) .and. ( wi .eq. b(9) ) ) goto 4110
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wi = 0
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go to 4110
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5070 wi = b(7)
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if ( ( wi .eq. b(8) ) .and. ( wi .eq. b(9) ) ) goto 4110
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(4) ) ) goto 4110
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if ( ( wi .eq. b(5) ) .and. ( wi .eq. b(3) ) ) goto 4110
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wi = 0
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go to 4110
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5080 wi = b(8)
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if ( ( wi .eq. b(7) ) .and. ( wi .eq. b(9) ) ) goto 4110
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if ( ( wi .eq. b(2) ) .and. ( wi .eq. b(5) ) ) goto 4110
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wi = 0
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go to 4110
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5090 wi = b(9)
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if ( ( wi .eq. b(7) ) .and. ( wi .eq. b(8) ) ) goto 4110
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if ( ( wi .eq. b(3) ) .and. ( wi .eq. b(6) ) ) goto 4110
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if ( ( wi .eq. b(1) ) .and. ( wi .eq. b(5) ) ) goto 4110
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wi = 0
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go to 4110
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end
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