not-really-math

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))

Original writeup (https://github.com/jkohhokj/hsctf8_writeups/blob/main/not-really-math.MD).