Why is __name__ == "__main__" not working?

Knapsack:What is wrong with the following code?

• I have made a code to test a knapsack problem, I have taken input from a file where i get total no. of items and total capacity into the variables 'items' and capacity 'respectively'. values and weights are array storing the respective items value and weight. Obviously maximize the value that can be contained in Knapsack(0-1 Knapsack prob) is the objective. Here is the code in Python: counter=0 def knapsack(i,j):     global counter     counter+=1     value=0     if(i==0 ):         value=0     else:         if v[i][j]<0:             if(j<weights[i]):                 value=knapsack(i-1,j)             else:                 value=max(knapsack(i-1,j),(values[i]+knapsack(i-1,j-weights[i])))     v[i][j]=value     return v[i][j] def solveIt(inputData):         global counter     # parse the input     lines = inputData.split('\n')     firstLine = lines[0].split()     items = int(firstLine[0])         capacity = int(firstLine[1])     global values     values= [0]     global weights     weights= [0]     for i in range(1, items+1):         line = lines[i]         parts = line.split()         values.append(int(parts[0]))         weights.append(int(parts[1]))     # Dynamic Programming Top to Bottm approach for filling the knapsack     value = 0     weight = 0     taken1 = [0 for i in range(items+1)]     taken=[0 for i in range(items)]     global v     v=[[-1 for x in range(capacity+1)] for x in range(items+1)]         value=knapsack(items,capacity)         tempi=items     tempc=capacity            print capacity     sumtotal=0         ####################################Backtracking     while (items!=0 and capacity!=0):         if(v[items][capacity]!=-1 and v[items-1][capacity]!=-1):             if v[items][capacity]!=v[items-1][capacity]:                 taken1[items]=1                 sumtotal+=weights[items]                 capacity=capacity-weights[items]                 items-=1             else:                 taken1[items]=0                 items-=1         else:             taken1[items]=0             items-=1    # prepare the solution in the specified output format     outputData = str(value) + ' ' + str(0) + '\n'     outputData += ' '.join(map(str, taken))             print values     print weights     print "Occuied capacity"+str(sumtotal)     print counter     print outputData     for i in range(1,tempi+1):         print taken1[i]     #return outputData ###avoid this code; nothing to do with algo import sys if __name__ == '__main__':     if len(sys.argv) > 1:         fileLocation = sys.argv[1].strip()         inputDataFile = open(fileLocation, 'r')         inputData = ''.join(inputDataFile.readlines())         inputDataFile.close()         print solveIt(inputData)     else:         print 'This test requires an input file.  Please select one from the data directory. (i.e. python http://solver.py ./data/ks_4_0)' ##################################################################################THe problem is that it works for many simple cases bt doesnt for some typical tough cases. Any help would be appreciated. Thanks in advance.

• Answer:

  Better if you post these sort of questions here: http://stackoverflow.com/