{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 7: Recursion"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.1, Page number: 219"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration, calculation and result\n",
"str = raw_input('Enter a string: ')\n",
"\n",
"print str"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter a string: HELLO\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"HELLO\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.2, Page number: 221"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration, calculation and result\n",
"str = raw_input('Enter a string: ')\n",
"\n",
"print str[::-1]"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter a string: HELLO\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"OLLEH\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.3, Page number: 224"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def fact (n) :\n",
" if n>0 :\n",
" return n * fact (n-1)\n",
" else :\n",
" return 1\n",
"\n",
"print ('Factorial of %d is %d' % (n, fact (n)))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 5\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Factorial of 5 is 120\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.4, Page number: 227"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def printnum (n) :\n",
" if n>0 :\n",
" printnum (n-1)\n",
" print n,\n",
"\n",
"print ('Counting up to %d' % n)\n",
"printnum (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 10\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Counting up to 10\n",
"1 2 3 4 5 6 7 8 9 10\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.5, Page number: 229"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def printeven (n) :\n",
"\tif not hasattr(printeven, \"x\") : \n",
"\t\tprinteven.x = 2\n",
" \n",
"\tif printeven.x <= n :\n",
"\t\tprint printeven.x,\n",
"\t\tprinteven.x = printeven.x + 2\n",
"\t\tprinteven (n)\n",
"\n",
"print ('Even numbers up to %d are' % n)\n",
"printeven (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 10\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Even numbers up to 10 are\n",
"2 4 6 8 10\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.6, Page number: 231"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def printodd (x, n) :\n",
"\tif x <= n : \n",
"\t\tprint x,\n",
"\t\tprintodd (x+2, n)\n",
"\n",
"print ('Odd numbers up to %d are' % n)\n",
"printodd (1, n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 10\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Odd numbers up to 10 are\n",
"1 3 5 7 9\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.7, Page number: 232"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def printnum (fro, to) :\n",
"\tif fro <= to : \n",
"\t\tprint fro,\n",
"\t\tprintnum (fro+1, to)\n",
"\n",
"print ('Number line for %d is' % n)\n",
"printnum (-n, n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 5\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Number line for 5 is\n",
"-5 -4 -3 -2 -1 0 1 2 3 4 5\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.8, Page number: 234"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def summate (n) :\n",
"\tif n > 0 : \n",
"\t\treturn n + summate (n-1)\n",
"\telse :\n",
"\t\treturn 0\n",
"\n",
"print ('Sum of first %d natural numbers is %d' % (n, summate (n)))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 10\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Sum of first 10 natural numbers is 55\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.9, Page number: 237"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def factors (n) :\n",
"\tif not hasattr(factors, \"i\") : \n",
"\t\tfactors.i = 1\n",
"\t\t\n",
"\tif factors.i <= n : \n",
"\t\tif n % factors.i == 0 :\n",
"\t\t\tprint factors.i,\n",
"\t\tfactors.i = factors.i + 1\n",
"\t\tfactors (n)\n",
"\n",
"print ('The factors of %d are' % n)\n",
"factors (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 28\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The factors of 28 are\n",
"1 2 4 7 14 28\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.10, Page number: 239"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def multiple (n) :\n",
"\tif not hasattr(multiple, \"i\") : \n",
"\t\tmultiple.i = 1\n",
"\t\t\n",
"\tif multiple.i <= 10 : \n",
"\t\tprint ('%d X %d = %d' % (n, multiple.i, n*multiple.i))\n",
"\t\tmultiple.i = multiple.i + 1\n",
"\t\tmultiple (n)\n",
"\n",
"print ('The first 10 multiples of %d are' % n)\n",
"multiple (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 6\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The first 10 multiples of 6 are\n",
"6 X 1 = 6\n",
"6 X 2 = 12\n",
"6 X 3 = 18\n",
"6 X 4 = 24\n",
"6 X 5 = 30\n",
"6 X 6 = 36\n",
"6 X 7 = 42\n",
"6 X 8 = 48\n",
"6 X 9 = 54\n",
"6 X 10 = 60\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.11, Page number: 241"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def checkprime (n) :\n",
" flag = 1\n",
" i = 2\n",
" while i<n and flag :\n",
" if n%i == 0 :\n",
" flag = 0\n",
" i = i+1\n",
" return flag\n",
"\n",
"result = checkprime (n)\n",
"\n",
"if result :\n",
" print ('The number %d is PRIME ' % n)\n",
"else :\n",
" print ('The number %d is COMPOSITE ' % n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 19\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The number 19 is PRIME \n"
]
}
],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.12, Page number: 243"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def Fibonacci (n) :\n",
"\tif n < 2 :\n",
"\t\treturn n\n",
"\telse :\n",
"\t\treturn Fibonacci (n-1) + Fibonacci (n-2)\n",
"\t\n",
"\n",
"print ('The %d terms of Fibonacci series are' % n)\n",
"for i in range (0, n) :\n",
"\tprint ('%d' % Fibonacci (i)),"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 10\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The 10 terms of Fibonacci series are\n",
"0 1 1 2 3 5 8 13 21 34\n"
]
}
],
"prompt_number": 12
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.13, Page number: 244"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"sum = n\n",
"\n",
"# Function declaration, calculation and result\n",
"def sumofdigit (n, sum) :\n",
" while sum>=10 :\n",
" sum = 0\n",
" while n>0 :\n",
" sum = sum + n%10\n",
" n = n/10\n",
" n = sum\n",
" return sum\n",
"\n",
"result = sumofdigit (n, sum)\n",
"\n",
"print ('Sum of digits of %d is %d' % (n, result))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 8626\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Sum of digits of 8626 is 4\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.14, Page number: 245"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def prime (n) :\n",
" for num in range (3, n+1) :\n",
" flag = 1\n",
" for i in range (2, num) :\n",
" if num % i == 0 : \n",
" flag = 0\n",
" if flag :\n",
" print ('%d ' % num),\n",
"\n",
"print ('Prime numbers upto %d are' % n)\n",
"prime (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 30\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Prime numbers upto 30 are\n",
"3 5 7 11 13 17 19 23 29 \n"
]
}
],
"prompt_number": 15
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.15, Page number: 246"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int (raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def pattern (n) :\n",
"\tif n > 0 :\n",
"\t\tpattern (n-1)\n",
"\t\tfor count in range (1, n+1) :\n",
"\t\t\tprint ('%d' % count),\n",
" \tprint\n",
" \t\n",
"pattern (n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 4\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"1\n",
"1 2\n",
"1 2 3\n",
"1 2 3 4\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.16, Page number: 249"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variable declaration\n",
"n = int(raw_input('Enter any number '))\n",
"\n",
"# Function declaration, calculation and result\n",
"def printline (x, total) :\n",
"\tif x > 0 :\n",
"\t\tprintline (x-1, total)\n",
"\t\tfor blk in range (1, total-x+1) :\n",
"\t\t\tprint ' ',\n",
"\t\tfor up in range (1, x+1) :\n",
"\t\t\tprint ('%d' % up),\n",
"\t\tdown = x-1\n",
"\t\twhile down>0 :\n",
"\t\t\tprint ('%d' % down),\n",
"\t\t\tdown = down-1\n",
"\t\tprint\n",
"\n",
"printline (n, n)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 4\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
" 1\n",
" 1 2 1\n",
" 1 2 3 2 1\n",
"1 2 3 4 3 2 1\n"
]
}
],
"prompt_number": 17
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.17, Page number: 253"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Function declaration, calculation and result\n",
"def listsum () :\n",
"\tn = int(raw_input('Enter any number '))\n",
"\tif n > 0 :\n",
"\t\treturn n + listsum ()\n",
"\telse :\n",
"\t\treturn 0\n",
"\t\t\n",
"sum = listsum ()\n",
"print ('Sum of list of numbers is %d' % sum)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 1\n"
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 2\n"
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number 3\n"
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter any number -4\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Sum of list of numbers is 6\n"
]
}
],
"prompt_number": 18
}
],
"metadata": {}
}
]
}