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Job Sequencing in ALGOL 60
Published on 18 April 2026 (Updated: 18 April 2026)
Welcome to the Job Sequencing in ALGOL 60 page! Here, you'll find the source code for this program as well as a description of how the program works.
Current Solution
begin
procedure usage;
begin
outstring(
1,
"Usage: please provide a list of profits and a list of deadlines\n"
);
stop
end usage;
comment Input a digit character from stdin and return the following:
- "0" to "9" maps to 0 to 9
- "+" maps to 10
- "-" maps to 11
- whitespace maps to 12
- comma maps to 13
- null byte maps to -1
- invalid bytes map to -2;
integer procedure indigit;
begin
comment Mapping:
- "0" to "9" maps to 1 to 10
- "+" maps to 11
- "-" maps to 12
- "\t" maps to 13
- "\r" maps to 14
- "\n" maps to 15
- " " maps to 16
- "," maps to 17
- null byte maps to 18
- invalid byte maps 0;
integer ch;
inchar(0, "0123456789+-\t\r\n ,", ch);
if ch < 1 then ch := -2
else if ch < 13 then ch := ch - 1
else if ch < 17 then ch := 12
else if ch = 17 then ch := 13
else ch := -1;
indigit := ch
end indigit;
comment Input an integer from stdin into 'result' and parse it.
The last character is read into 'ch'.
return true if integer is valid, false otherwise;
boolean procedure inValidInteger(result, ch, allowComma);
value allowComma;
integer result, ch;
boolean allowComma;
begin
boolean valid, commaFound;
integer s;
result := 0;
valid := false;
commaFound := false;
s := 1;
comment Ignore whitespace;
whiteloop:
ch := indigit;
if ch = 12 then goto whiteloop;
comment Process signs: ignore "+" and invert sign if "-";
signloop:
if ch = 10 | ch = 11 then
begin
if ch = 11 then s := -s;
ch := indigit;
goto signloop
end;
comment Indicate valid if "0" to "9";
if ch >= 0 & ch <= 9 then valid := true;
comment Process digits: update value;
valueloop:
if ch >= 0 & ch <= 9 then
begin
comment Invalid if overflow or underflow;
if (s > 0 & (maxint - ch) % 10 < result) |
(s < 0 & (-1 - maxint + ch) % 10 > result) then valid := false;
result := result * 10 + s * ch;
ch := indigit;
goto valueloop
end;
comment If comma not allowed, ignore characters until end
input. If comma allowed, ignore characters until comma
or end of input. Indicate if comma found;
ignoreloop:
if !(ch = -1 | (allowComma & ch = 13)) then
begin
if ch != 12 & ch != 13 then valid := false;
if ch = 13 then
begin
commaFound := true;
if !allowComma then valid := false
end;
ch := indigit;
goto ignoreloop
end;
comment If comma found, indicate last character is comma;
if commaFound then ch := 13;
inValidInteger := valid
end inValidInteger;
comment Returns length of array if valid, -1 otherwise;
integer procedure inIntegerArray(arr, maxLen);
value maxLen;
integer array arr;
integer maxLen;
begin
integer arrLen, val, ch;
boolean valid;
arrLen := 0;
comment Get value with possible comma (13). Indicate invalid,
if invalid integer. Otherwise, append value to array if
no invalid values and there is room;
itemloop:
if !inValidInteger(val, ch, true) then arrLen := -1
else if arrLen >= 0 & arrLen < maxLen then
begin
arrLen := arrLen + 1;
arr[arrLen] := val
end;
comment Repeat until end of input;
if ch != -1 then goto itemloop;
inIntegerArray := arrLen
end inIntegerArray;
comment Job sequencing with deadlines. Source
https://www.techiedelight.com/job-sequencing-problem-deadlines/;
integer procedure jobSequencing(profits, deadlines, n);
value n;
integer array profits, deadlines;
integer n;
begin
integer i, j, d, maxDeadline, totalProfit;
integer array jobs[1:n, 1:2];
comment Set up jobs and get maximum deadline;
maxDeadline := 0;
for i := 1 step 1 until n do
begin
d := deadlines[i];
jobs[i, 1] := profits[i];
jobs[i, 2] := d;
if d > maxDeadline then maxDeadline := d
end;
comment Initialize total profit;
totalProfit := 0;
begin
comment Initialize slots;
integer array slots[1:maxDeadline];
for i := 1 step 1 until maxDeadline do slots[i] := 0;
comment Sort jobs by profit then deadline;
bubbleSort(jobs, n);
for i := 1 step 1 until n do
begin
comment For each job, see if there is available slot at or
before the deadline. If so, store this job index in that
slot and update total profit;
j := jobs[i, 2] + 1;
searchloop:
j := j - 1;
if j >= 1 then
begin
if slots[j] > 0 then goto searchloop;
slots[j] := i;
totalProfit := totalProfit + jobs[i, 1]
end
end;
end;
jobSequencing := totalProfit
end jobSequencing;
comment Source https://en.wikipedia.org/wiki/Bubble_sort#Optimizing_bubble_sort;
procedure bubbleSort(jobs, numJobs);
value numJobs;
integer array jobs;
integer numJobs;
begin
integer i, n, newN;
n := numJobs;
sortloop:
newN := 1;
for i := 2 step 1 until n do
begin
if compareJobs(jobs, i - 1, i) > 0 then
begin
swapJobs(jobs, i - 1, i);
newN := i
end
end;
n := newN;
if n > 2 then goto sortloop
end bubbleSort;
comment Prioritize job with highest profit then longest deadline.
For jobs, profits are in column 1, deadlines as in column 2.
Returns:
- negative if first job has higher priority
- zero if both jobs have same priority
- positive if second job has higher priority;
integer procedure compareJobs(jobs, i, j);
value i, j;
integer array jobs;
integer i, j;
begin
compareJobs := if jobs[i, 1] != jobs[j, 1] then jobs[j, 1] - jobs[i, 1]
else jobs[j, 2] - jobs[i, 2]
end compareJobs;
procedure swapJobs(jobs, i, j);
value i, j;
integer array jobs;
integer i, j;
begin
procedure swap(a, b);
integer a, b;
begin
integer t;
t := a;
a := b;
b := t
end swap;
swap(jobs[i, 1], jobs[j, 1]);
swap(jobs[i, 2], jobs[j, 2])
end swapJobs;
integer argc, numProfits, numDeadlines, result;
integer array profits[1:100], deadlines[1:100];
comment Get number of parameters. Exit if too few;
ininteger(0, argc);
if argc < 2 then usage;
comment Get profits from 1st argument. Exit if invalid;
numProfits := inIntegerArray(profits, 100);
if numProfits < 1 then usage;
comment Get deadlines from 2nd argument. Exit if invalid or the number
of deadlines is not the same as the number of profits;
numDeadlines := inIntegerArray(deadlines, 100);
if numDeadlines != numProfits then usage;
comment Find best sum of profits and display result;
result := jobSequencing(profits, deadlines, numProfits);
outinteger(1, result);
outstring(1, "\n")
end
Job Sequencing in ALGOL 60 was written by:
- rzuckerm
If you see anything you'd like to change or update, please consider contributing.
How to Implement the Solution
No 'How to Implement the Solution' section available. Please consider contributing.
How to Run the Solution
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