Anonymous user
Pascal's triangle/Puzzle: Difference between revisions
→{{header|Oz}}: Add example Python code
(Ada solution added) |
(→{{header|Oz}}: Add example Python code) |
||
Line 234:
{Application.exit 0}
end</ocaml>
=={{header|Python}}==
Python 2.4, but should work with later versions as well.
<Python># Pyramid solver
# [151]
# [ ] [ ]
# [ 40] [ ] [ ]
# [ ] [ ] [ ] [ ]
#[ X ] [ 11] [ Y ] [ 4 ] [ Z ]
# X -Y + Z = 0
def combine( snl, snr ):
cl = {}
if type(snl ) == type(1):
cl['1'] = snl
elif type(snl) == type('X'):
cl[snl] = 1
else:
cl.update( snl)
if type(snr ) == type(1):
n = cl.get('1', 0)
cl['1'] = n + snr
elif type(snr) == type('X'):
n = cl.get(snr, 0)
cl[snr] = n + 1
else:
for k,v in snr.items():
n = cl.get(k, 0)
cl[k] = n+v
return cl
def constrain(nsum, vn ):
nn = {}
nn.update(vn)
n = nn.get('1', 0)
nn['1'] = n - nsum
return nn
def makeMatrix( constraints ):
vmap = set()
for c in constraints:
vmap.update( c.keys())
vmap.remove('1')
nvars = len(vmap)
vmap = sorted(list(vmap)) # sort here so output is in sorted order
mtx = []
for c in constraints:
row = []
for vv in vmap:
row.append(1.0* c.get(vv, 0))
row.append(-1.0*c.get('1',0))
mtx.append(row)
if len(constraints) == nvars:
print 'System appears solvable'
elif len(constraints) < nvars:
print 'System is not solvable - needs more constraints.'
return mtx, vmap
def SolvePyramid( vl, cnstr ):
vl.reverse()
constraints = [cnstr]
lvls = len(vl)
for lvln in range(1,lvls):
lvd = vl[lvln]
for k in range(lvls - lvln):
sn = lvd[k]
ll = vl[lvln-1]
vn = combine(ll[k], ll[k+1])
if sn is None:
lvd[k] = vn
else:
constraints.append(constrain( sn, vn ))
print 'Constraint Equations:'
for cstr in constraints:
fset = ('%d*%s'%(v,k) for k,v in cstr.items() )
print ' + '.join(fset), ' = 0'
mtx,vmap = makeMatrix(constraints)
MtxSolve(mtx)
d = len(vmap)
for j in range(d):
print vmap[j],'=', mtx[j][d]
def MtxSolve(mtx):
# Simple Matrix solver...
mDim = len(mtx) # dimension---
for j in range(mDim):
rw0= mtx[j]
f = 1.0/rw0[j]
for k in range(j, mDim+1):
rw0[k] = rw0[k] * f
for l in range(1+j,mDim):
rwl = mtx[l]
f = -rwl[j]
for k in range(j, mDim+1):
rwl[k] = rwl[k] + f * rw0[k]
# backsolve part ---
for j1 in range(1,mDim):
j = mDim - j1
rw0= mtx[j]
for l in range(0, j):
rwl = mtx[l]
f = -rwl[j]
rwl[j] = rwl[j] + f * rw0[j]
rwl[mDim] = rwl[mDim] + f * rw0[mDim]
return mtx
p = [ [151], [None,None], [40,None,None], [None,None,None,None], ['X', 11, 'Y', 4, 'Z'] ]
addlConstraint = { 'X':1, 'Y':-1, 'Z':1, '1':0 }
SolvePyramid( p, addlConstraint)
</Python>
Output:
<pre>Constraint Equations:
-1*Y + 1*X + 0*1 + 1*Z = 0
-18*1 + 1*X + 1*Y = 0
-73*1 + 5*Y + 1*Z = 0
System appears solvable
X = 5.0
Y = 13.0
Z = 8.0
</pre>
The Pyramid solver is not restricted to solving for 3 variables, or just this particular pyramid.
| |||