yagihashoo_ctf_rpn.py

#!/usr/bin/python

import socket
host = 'rg-ctf.yagihashoo.com'
port = 'secret'

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((host,port))

while True:
    string = sock.recv(524288)
    if string != "":
        print string
    else:
        break
    if '=>' in string:
        q = string[:-4].split(' ')
        stack = []
        print q
        print len(q)
        while len(q) > 0:
            # print q, stack
            stack.append(q.pop(0))
            if not stack[-1].isdigit() and len(stack[-1]) == 1:
                obj = stack.pop()
                num = float(stack.pop(-1))
                if obj == '+':
                    ans = float(stack.pop()) + num
                elif obj == '-':
                    ans = float(stack.pop()) - num
                elif obj == '*':
                    ans = float(stack.pop()) * num
                elif obj == '/':
                    ans = float(stack.pop()) / num
                stack.append(ans)
            # print q
        if stack[0] < 0 and stack[0] - int(stack[0]) != 0:
            # print stack[0]
            stack[0] -= 1
        sock.sendall(str(int(stack[0])) + '\n')
sock.close()