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Step 9:  If ch is equal to space then go to Step 10 else go to Step 13.
                 Step 10: If word = del_word then go to Step 12.
                 Step 11: Add word to new_sentence and then add space to new_sentence. Go to Step 14

                 Step 12: Initialise word to null, go to Step 14.
                 Step 13: Add ch to word.
                 Step 14: Increment i by 1.

                 Step 15: Display new_sentence.
                 Step 16: Stop.

                 3.5.7 Recursive Algorithms

                                                                           b
                 Problem 18: Write a recursive algorithm to find power(a, b) or a .
                 Step 1:  Start.
                 Step 2:  Accept a and b.

                 Step 3:  If b = 1 then return 1, else go to Step 3.
                 Step 4:  Return a x power(a, b-1).
                 Step 5:  Stop.

                 Problem 19: Write a recursive algorithm to find the sum of the digits of a number sumofdigit(num).
                 Step 1:  Start.
                 Step 2:  If num = 0 then return 0, else go to Step 3.
                 Step 3:  Return num % 10 + sumofdigit(num/10).
                 Step 4:  Stop.


                 3.5.8 Algorithms on Operations in STACK
                 Stack is a data structure that follows LIFO (Last in first out principle).


                        Note:  Stack is covered in detail in later part of this book.

                 Problem 20:

                 a.  Pushing data into stack assuming top = -1
                   Step 1:  Start.
                   Step 2:   If top = size then print “Stack full .. overflow”, and go to step 5.

                   Step 3:  Increment top by 1.
                   Step 4:  Set array[top] = x.
                   Step 5:  Stop.
                 b.  Popping data from stack

                   Step 1:  Start.
                   Step 2:  If top = -1 then return -999.
                   Step 3:  Store value = array[top].

                   Step 4:  Decrease top by 1.




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                                                                            Implementation of Algorithms to Solve Problems  113
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