The file looks like this:

```
183 183 0
548 3000548 5
91 8000091 5
41 2000041 8
95 1000095 1
296 296 4
625 625 2
399 4000399 6
904 6000904 7
386 8000386 8
...
```

The following script can calculate the code:

```python
import re
import time

with open('/tmp/Given_File.txt', 'r') as f:
lines = f.readlines()

l = [0 for i in range(10**7)]

for line in lines:
m = re.search(r'^(\d+) (\d+) (\d+)$', line)
if(m):
a = int(m.group(1))
b = int(m.group(2))
c = int(m.group(3))
for i in range(a,b):
l[i-1] = (l[i-1] + c) % 10
else:
print("Bad line: '{}'".format(line))

p = 1
for x in l:
if(x != 0):
p = p * x % 999999937

print(p)
```

However, executing it on the original file would take much too long. We need to optimise the number codes first.

First, we are reducing redundancy by aggregating lines with the same a and b values (`100 100 1` and `100 100 2` can be aggregated to `100 100 3`):

```python
import re

with open('/tmp/sorted.txt', 'r') as f:
lines = f.readlines()

opt = {}
n=0
ts1 = time.time()
for line in lines:
n += 1
m = re.search(r'^(\d+) (\d+) (\d+)$', line)
if(m):
a = int(m.group(1))
b = int(m.group(2))
c = int(m.group(3))
if( (a,b) in opt):
opt[(a,b)] += c
else:
opt[(a,b)] = c
else:
print("Bad line: '{}'".format(line))

for key in opt:
a,b = key
print('{} {} {}'.format(a, b, opt[key]))
```

With those optimisations, the running time of the script would still be a few hours. We can do some better, by removing some overlapping intervals:

```python
import re

with open('/tmp/optimized.txt', 'r') as f:
lines = f.readlines()

def optimize(d:dict):
for a in d:
bs = list(d[a].keys())
list.sort(bs, reverse=True)
if(bs[-1] == a):
bs.remove(a)
if(len(bs) > 1):

b = bs[0]
c = d[a][b]
nextb = bs[1]
if(not nextb in d[a]):
d[a][nextb] = 0
d[a][nextb] += c
if(not nextb in d):
d[nextb] = {}
if(not b in d[nextb]):
d[nextb][b] = 0
d[nextb][b] += c
del d[a][b]
return d, True

return d, False

opt = {}
n=0
ts1 = time.time()
for line in lines:
n += 1
m = re.search(r'^(\d+) (\d+) (\d+)$', line)
if(m):
a = int(m.group(1))
b = int(m.group(2))
c = int(m.group(3))
if(not a in opt):
opt[a] = {}
opt[a][b] = c

opt2, optimized = optimize(opt)
while optimized:
opt2, optimized = optimize(opt2)

for a in opt2:
for b in opt2[a]:
c = opt2[a][b]
print('{} {} {}'.format(a, b, c))
```

After this (still not perfect) optimisation, the script spits out the code after ~40 minutes:

Flag: **HackTM{585778044}**