Not Really Math Writeup

Complete writeup of the "Not Really Math" algo challenge from HSCTF 8.

Description

Summary: change the order of operations in a math formula with only addition (a) and multiplication (m) to having addition operations first and mulitplication operations second.

Sample Input:

2m3a19m2a38m1

Sample Output:

1760

Explanation:

$2(3+19)(2+38)1 = 1760$

Code Concept:
Add ( and ) around the numbers that should be added and change a to + and m to *
Then plug into python calculator to solve

import sys
print(sys.argv[1])
new = list(sys.argv[1])
l = ["m","a"]
c = 0
while c < len(new)-1:
    if new[c] not in l and new[c+1] not in l:
        new[c] += new[c+1]
        del new[c+1]
        c -= 1
    c += 1
c = 0
while c < len(new):
    if new[c] == "a":
        if new[c-1] != ")":
            new.insert(c-1,"(")
            new.insert(c+3,")")
            new[c+1] = "+"
        else:
            new.insert(c-1,"+")
            new.insert(c, new[c+2])
            del new[c+2]
            del new[c+2]
    elif new[c] == "m":
        new[c] = "*"
    c += 1
for x in new:
    if x != "(" and x!= ")" and x!= "+" and x!="*":
        x = int(x)
new = ''.join(new)
print(eval(new)%(pow(2,32)-1))