data structure - stack

1)         STACK USING ARRAY: -

            1)         Procedure PUSH (VAL)

                        [Description]

                        Step 1: [Check stack is empty or not]

                                    If TOS >=SIZE-1

                                    Then

                                                Write (‘Stack Overflow……..’)

                                                Return

                        Step 2: [Increment TOS by 1]

                                   

                                    TOS ¬ TOS+1

                        Step 3: [Assign value]

                                   

                                    S [TOS] ¬ VAL

                        Step 4: [Finished]

                       

                                    Return

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2)            Function POP ( )

            [Description]

            Step 1: [Check stack is empty or not]

                        If TOS < 0

                        Then

                                    Write (‘Stack Underflow…..’)

                                    Return -1

            Step 2: [Decrement pointer]

           

                        VAL ¬ S [TOS]

                        TOS ¬ TOS – 1

            Step 3: [Return deleted value]

                        Return VAL

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2)                  Function PEEP ( KEY)

            [Description]

            Step 1: [Find the element number]

                        INDEX ¬ TOS – KEY +1

            Step 2: [Check stack is empty or not]

                        If INDEX < 0

                        Then

                                    Write (‘Stack Underflow…..’)

                                    Return -1

            Step 3: [Return the element from stack]

                        Return S [INDEX]

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3)                  Function CHANGE ( KEY , VAL)

            [Description]

            Step 1: [Find the element number]

                        INDEX ¬ TOS – KEY +1

            Step 2: [Check stack is empty or not]

                        If INDEX < 0

                        Then

                                    Write (‘Stack Underflow…..’)

                                    Return -1

            Step 3: [Change the value from stack]

                        S [INDEX] ¬VAL

                        Return 1

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4)                  Procedure PRINT ( )

            [Description]

                        Step 1: [Check Stack is empty or not]

                                    If TOS < 0

                                    Then

                                                Write (‘Stack Underflow……’)

                                                Return

                       

                                    Step 2: [Print the value from stack]

           

                                                Repeat For I = TOS, TOS-1…….While I >= 0

                                                Write S [I]

           

                                    Step 3: [Finished]

                                                Return

1)         STACK USING LINK LIST: -

            1)         Procedure PUSH (VAL)

                        [Description]

                        Step 1: [Allocate the memory]

                                    NEWNODE  Ü NODE

                        Step 2: [Read the INFO]

                                   

                                    Read (INFO (NEWNODE))

                                   

                        Step 3: [Arrange the address]

                                   

                                    NEXT (NEWNODE) ¬ TOS

                                    TOS ¬ NEWNODE

                        Step 4: [Finished]

                                    Return

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3)            Function POP ( )

            [Description]

            Step 1: [Check stack is empty or not]

                        If TOS = NULL

                        Then

                                    Write (‘Stack Underflow…..’)

                                    Return -1

            Step 2: [Assign deleted value in VAL]

           

                        VAL ¬ INFO (TOS)

            Step 3: [Assign the address of next NODE in TOS]

                        TOS ¬ NEXT [TOS]

                        Return VAL

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5)                  Function PEEP ( KEY)

            [Description]

            Step 1: [Store TOS into TEMP]

                       

                        TEMP ¬ TOS

            Step 2: [Repeat the loop up to last NODE]

                       

                        I ¬ 1

                        Repeat While TEMP # NULL

                                    If I = KEY

                                    Then

                                                Return 1

                                    Else

                                                TEMP ¬ (NEXT) TEMP

                                                I ¬ I+1

                                               

            Step 3: [KEY not found, so return false]

                       

                        Return -1

            --------------------------------------------------------------------------------------

6)                  Function CHANGE ( KEY , VAL)

            [Description]

            Step 1: [Store TOS into TEMP]

                        TEMP ¬ TOS

            Step 2: [Repeat the loop up to last NODE]

                       

                        I ¬ 1

                        Repeat While TEMP # NULL

                                    If I = KEY

                                    Then

                                                INFO (TEMP) ¬ VAL

                                                Return 1

                                    Else

                                                TEMP ¬ (NEXT) TEMP

                                                I ¬ I+1

                                               

            Step 3: [KEY not found, so return false]

                       

                        Return -1

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7)                  Procedure PRINT ( )

            [Description]

            Step 1: [Store TOS into TEMP]

                        TEMP ¬ TOS

                        Step 2: [Repeat the loop till the last NODE]

                                   

                                    Repeat While TEMP # NULL

                                                Write INFO (TEMP)

                                                TEMP ¬ NEXE (TEMP)

                       

                        Step 3: [Finished]

                       

                                    Return