Internet Problem Solving Contest 2015 J2

J2.cpp

#include <cstdio>

bool check(unsigned short ax, unsigned short bx) {
    unsigned short tmp;

    for (int i=0; i<23; i++) {
        if (bx < ax) return false;
        if (ax == 0) return false;
        bx -= ax;
        tmp = ax;
        ax = bx;
        bx = tmp;
    }

    return true;
}

int main() {
    for (unsigned int a=0xffff; a>=0; a--) {
        for (unsigned int b=a; b<=a*2 && b<=0xffff; b++) {
            if (check((unsigned short)a, (unsigned short)b)) printf("%u %u\n", a, b);
        }
        if (a == 0) break;
    }
}

J2.py

ax = 28657
bx = 46368
cx = 0x27
s = ";M\xb3\xfcd\x89\xdc\x0cz\xa2\xe6U\xca\xd1wm\xaf\x04[\x84\xe4q \x97&E\xba\xe4^\x86\xcd1C\xa0\rR\x86\xf2p\r\n$"
i = 0
ans = ""
while cx != 0:
    ans +=  chr(ord(s[i]) ^ (ax/0x100))
    ax += bx
    ax %= 0x10000
    i += 1
    cx -= 1
print ans