Submission #70103908

---

Source Code Expand

from sys import stdin
def input():
    return stdin.readline().rstrip("\n")
def ok(c, x, n):
    return n and (n ^ c) % n == x


def solve2(c: int, x: int):
    if ok(c, x, c ^ x):
        return c ^ x
    # msb
    cm = c.bit_length() - 1
    c2 = 1 << cm
    if x < c2:
        # ?
        assert False
        return "??"
    if x < 2 * c2:
        if x > c:
            return -1
        n = 2 * c2 + (c - x) // 2
        if (n ^ c) % n != x:
            n = -1
        return n
    if x >> cm & 1:
        return -1
    return c ^ x

def solve():
    c, x = map(lambda s_: int(s_), input().split())
    print(solve2(c, x))
case_t = 1
case_t = int(input())
for _ in [None] * case_t:
    solve()

Submission Info

Judge Result