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Merge_Sort
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197 lines (167 loc) · 5.49 KB
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*&---------------------------------------------------------------------*
*& Report Z_ALGORITHMS_MERGE_SORT
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*
REPORT z_algorithms_merge_sort.
DATA gt_digits TYPE abadr_tab_int4.
INITIALIZATION.
PERFORM f_populate_data CHANGING
gt_digits.
START-OF-SELECTION.
PERFORM f_write_result USING
gt_digits
'Before'.
PERFORM f_merge_sort USING gt_digits
1
10.
END-OF-SELECTION.
PERFORM f_write_result USING
gt_digits
'After'.
*&---------------------------------------------------------------------*
*& Form F_MERGE_SORT
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
* -->P_LT_DIGITS text
* -->P_1 text
* -->P_8 text
*----------------------------------------------------------------------*
FORM f_merge_sort USING ut_digits TYPE abadr_tab_int4
value(uv_start)
value(uv_end).
DATA:
lv_temp TYPE p DECIMALS 2,
lv_middle TYPE int4,
lv_middle_next TYPE int4.
IF uv_start < uv_end.
lv_temp = FLOOR( ( uv_start + uv_end ) / 2 ).
lv_middle = lv_temp.
lv_middle_next = lv_middle + 1.
PERFORM f_merge_sort USING ut_digits
uv_start
lv_middle.
PERFORM f_merge_sort USING ut_digits
lv_middle_next
uv_end.
PERFORM f_merge USING ut_digits
uv_start
lv_middle
uv_end.
ENDIF.
ENDFORM. " F_MERGE_SORT
*&---------------------------------------------------------------------*
*& Form f_populate_data
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
* <--P_LT_DIGITS text
*----------------------------------------------------------------------*
FORM f_populate_data CHANGING ct_digits TYPE abadr_tab_int4.
DATA:
lv_int4 TYPE int4.
DO 10 TIMES.
CALL FUNCTION 'GENERAL_GET_RANDOM_INT'
EXPORTING
range = 100
IMPORTING
random = lv_int4.
APPEND lv_int4 TO ct_digits.
ENDDO.
* DO 10 TIMES.
* CASE sy-index.
* WHEN 1.
* lv_int4 = 12.
* WHEN 2.
* lv_int4 = 9.
* WHEN 3.
* lv_int4 = 3.
* WHEN 4.
* lv_int4 = 7.
* WHEN 5.
* lv_int4 = 14.
* WHEN 6.
* lv_int4 = 11.
* WHEN 7.
* lv_int4 = 6.
* WHEN 8.
* lv_int4 = 2.
* WHEN 9.
* lv_int4 = 10.
* WHEN 10.
* lv_int4 = 5.
* WHEN OTHERS.
* ENDCASE.
* APPEND lv_int4 TO ct_digits.
* ENDDO.
ENDFORM. " f_populate_data
*&---------------------------------------------------------------------*
*& Form F_WRITE_RESULT
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
* -->P_LT_DIGITS text
*----------------------------------------------------------------------*
FORM f_write_result USING
ut_digits TYPE abadr_tab_int4
uv_title TYPE string.
DATA lv_int4 TYPE int4.
WRITE:
uv_title,
/.
LOOP AT ut_digits INTO lv_int4.
WRITE lv_int4.
ENDLOOP.
ENDFORM. " F_WRITE_RESULT
*&---------------------------------------------------------------------*
*& Form F_MERGE
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
* -->P_UT_DIGITS text
* -->P_UV_START text
* -->P_LV_MIDDLE text
* -->P_UV_END text
*----------------------------------------------------------------------*
FORM f_merge USING
ut_digits TYPE abadr_tab_int4
uv_start TYPE int4
uv_middle TYPE int4
uv_end TYPE int4.
DATA:
lv_digit TYPE int4,
lv_middle_next TYPE int4,
lv_index_l TYPE sy-index VALUE 1,
lv_index_r TYPE sy-index VALUE 1.
DATA:
lt_seq_l TYPE abadr_tab_int4,
ls_seq_l LIKE LINE OF lt_seq_l,
lt_seq_r TYPE abadr_tab_int4,
ls_seq_r LIKE LINE OF lt_seq_r.
FIELD-SYMBOLS:
<fs_digit> TYPE int4.
lv_middle_next = uv_middle + 1.
LOOP AT ut_digits INTO lv_digit FROM uv_start TO uv_middle.
APPEND lv_digit TO lt_seq_l.
ENDLOOP.
LOOP AT ut_digits INTO lv_digit FROM lv_middle_next TO uv_end.
APPEND lv_digit TO lt_seq_r.
ENDLOOP.
* Put a sentinel on the bottom
APPEND 999 TO lt_seq_l.
APPEND 999 TO lt_seq_r.
LOOP AT ut_digits ASSIGNING <fs_digit> FROM uv_start TO uv_end.
READ TABLE lt_seq_l INTO ls_seq_l INDEX lv_index_l.
READ TABLE lt_seq_r INTO ls_seq_r INDEX lv_index_r.
IF ls_seq_l < ls_seq_r.
<fs_digit> = ls_seq_l.
lv_index_l = lv_index_l + 1.
ELSE.
<fs_digit> = ls_seq_r.
lv_index_r = lv_index_r + 1.
ENDIF.
ENDLOOP.
ENDFORM. " F_MERGE