1.  

import os,sys

def getSuffix(s):
   tmp = s.split('.')
   if len(tmp) == 1: return None
   return tmp[-1]

def inspectFileNames(dct,dr,flst):
   for f in flst:
      suff = getSuffix(f)
      if suff == None: continue
      if suff in dct.keys():
         dct[suff] += 1
      else:
         dct[suff] = 1

def countLikeFiles():
   fileGrps =  {}
   os.path.walk('.',inspectFileNames,fileGrps)
   return fileGrps

try: os.mkdir('testcase')
except: pass
os.chdir('testcase')
top = os.getcwd()
try:
   f = open('abc.x','w')
   f.close()
   f = open('def.y','w')
   f.close()
except: pass
try: os.mkdir('a')
except: pass
os.chdir('a')
try:
   f = open('ghi.y','w')
   f.close()
except: pass
os.chdir(top)

print countLikeFiles()

2.

class mtrx:
   def __init__(self,x,nr):
      self.m = x
      self.nr = nr
      self.nc = len(x) / nr
   def getElement(self,i,j):
      return self.m[i*self.nc+j]
   def putElement(self,i,j,val):
      self.m[i*self.nc+j] = val
   def mulvec(self,v):
      vout = self.nr * [0] 
      for r in range(self.nr):
         s = 0
         for c in range(self.nc):
            s += self.getElement(r,c) * v[c]
         vout[r] = s
      return vout

z = mtrx([1,2,3,8,9,10],3)
print z.getElement(1,1)  # 8
z.putElement(1,0,12)
print z.m  # [1,2,12,8,9,10]
print z.getElement(1,0)  # 12
print z.mulvec([5,-2])  # [1,44,25]