Job Sequencing in Algol68

Published on 06 February 2023 (Updated: 06 February 2023)

Welcome to the Job Sequencing in Algol68 page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

``````MODE PARSEINT_RESULT = STRUCT(BOOL valid, INT value, STRING leftover);
MODE PARSEINTLIST_RESULT = STRUCT(BOOL valid, REF []INT values);

PROC parse int = (REF STRING s) PARSEINT_RESULT:
(
BOOL valid := FALSE;
REAL r := 0.0;
INT n := 0;
STRING leftover;

# Associate string with a file #
FILE f;
associate(f, s);

# On end of input, exit if valid number not seen. Otherwise ignore it #
on logical file end(f, (REF FILE dummy) BOOL:
(
IF NOT valid THEN done FI;
TRUE
)
);

# Exit if value error #
on value error(f, (REF FILE dummy) BOOL: done);

# Convert string to real number #
get(f, r);

# If real number is in range of an integer, convert to integer. Indicate integer is valid if same as real #
IF ABS r <= max int
THEN
n := ENTIER(r);
valid := (n = r)
FI;

# Get leftover string #
get(f, leftover);

done:
close(f);
PARSEINT_RESULT(valid, n, leftover)
);

PROC count list items = (STRING s) INT:
(
INT count := 1;
FOR k TO UPB s
DO
IF s[k] = ","
THEN
count +:= 1
FI
OD;

count
);

PROC parse int list = (REF STRING s) PARSEINTLIST_RESULT:
(
BOOL valid := FALSE;
STRING leftover := s;
INT num list items = count list items(s);
HEAP [num list items]INT values;

# Repeat while valid value #
FOR k TO num list items
DO
# Get next integer value and update leftover string #
PARSEINT_RESULT result = parse int(leftover);
valid := valid OF result;
leftover := leftover OF result;

# Append the integer value to list #
values[k] := value OF result;

# Do nothing if end of string #
IF leftover = ""
THEN
SKIP
# Skip comma if leftover string starts with comma #
ELIF leftover[1] = ","
THEN
leftover := leftover[2:]
# Otherwise indicate invalid #
ELSE
valid := FALSE
FI
UNTIL NOT valid
OD;

PARSEINTLIST_RESULT(valid, values)
);

PROC usage = VOID: printf((\$gl\$, "Usage: please provide a list of profits and a list of deadlines"));

# Job details #
MODE JOB = STRUCT(INT id, INT profit, INT deadline);

# Compare 2 jobs #
OP <= = (JOB job1, JOB job2) BOOL:
(
# Prioritize by profit, then deadline #
(profit OF job1 /= profit OF job2 | profit OF job1 - profit OF job2 > 0 | deadline OF job1 - deadline OF job2 >= 0)
);

COMMENT
Source: https://en.wikipedia.org/wiki/Quicksort#Lomuto_partition_scheme
COMMENT
PROC quick sort = (REF []JOB values) VOID:
(
quick sort rec(values, 1, UPB values)
);

PROC quick sort rec = (REF []JOB values, INT lo, INT hi) VOID:
(
IF lo < hi AND lo >= 1
THEN
# Partition array and get pivot value #
INT p := partition(values, lo, hi);

# Sort left side of partition #
quick sort rec(values, lo, p - 1);

# Sort right side of partition #
quick sort rec(values, p + 1, hi)
FI
);

PROC partition = (REF []JOB values, INT lo, INT hi) INT:
(
# Choose last value as pivot #
JOB pivot = values[hi];

# Set temporary pivot index #
INT i := lo - 1;

# Swap elements less than or equal to pivot, and increment temporary index #
FOR j FROM lo TO hi - 1
DO
IF values[j] <= pivot
THEN
i +:= 1;
swap(values, i, j)
FI
OD;

# Move pivot to correct position #
i +:= 1;
swap(values, i, hi);

i
);

PROC swap = (REF []JOB values, INT a, INT b) VOID:
(
JOB temp := values[a];
values[a] := values[b];
values[b] := temp
);

PROC max = (INT a, INT b) INT: (a > b | a | b);

COMMENT
COMMENT
PROC job sequencing = (REF []INT profits, REF []INT deadlines) REF []JOB:
(
# Set up job details and longest deadline #
INT n = UPB profits;
HEAP [n]JOB jobs;
FOR k TO n
DO
OD;

# Initialize job slots #
DO
slots[k] := JOB(0, 0, 0)
OD;

# Sort jobs by profit then deadline #
quick sort(jobs);

FOR i TO n
DO
# For each job, see if there is available slot at or before the deadline #
# if so, store this job in that slot #
BOOL slot found := FALSE;
FOR j FROM deadline OF jobs[i] DOWNTO 1
WHILE NOT slot found
DO
IF id OF slots[j] < 1
THEN
slots[j] := jobs[i];
slot found := TRUE
FI
OD
OD;

slots
);

# Get total profit #
PROC get total profit = (REF []JOB jobs) INT:
(
INT total := 0;
FOR k TO UPB jobs
DO
total +:= profit OF jobs[k]
OD;

total
);

# Parse 1st command-line argument #
STRING s := argv(4);
PARSEINTLIST_RESULT list result := parse int list(s);
REF []INT profits := values OF list result;
IF NOT valid OF list result
THEN
usage;
stop
FI;

# Parse 2nd command-line argument #
s := argv(5);
list result := parse int list(s);
REF []INT deadlines := values OF list result;
IF NOT valid OF list result OR UPB deadlines /= UPB profits
THEN
usage;
stop
FI;

# Get job sequence #
REF []JOB sequence := job sequencing(profits, deadlines);

# Get total profit and display #
INT total profit := get total profit(sequence);
printf((\$gl\$, whole(total profit, 0)))

``````

Job Sequencing in Algol68 was written by:

• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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How to Run the Solution

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