枚举二进制数中是哪一位错了，求出之后再与三进制数比较，如果有且只有一位不同，那么就是这个数。

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#define R register


#define LL long long


using namespace std;

char a[100], b[100];
inline void minn(R int &a, const int b) { a < b ? 0 : a = b; }
inline int ab(R int x) { return x < 0 ? -x : x; }

signed main() {
    scanf("%s", a + 1);
    scanf("%s", b + 1);
    R int num = 0, tmp = 0;
    R int la = strlen(a + 1), lb = strlen(b + 1);
    for (R int i = 1; i <= la; ++i) num = num << 1 | (a[i] - '0');
    for (R int i = 1; i <= lb; ++i) tmp = tmp * 3 + b[i] - '0';
    for (R int i = 1; i <= la; ++i) {
        R int ans = num ^ (1 << (la - i));
        R int tt = ab(ans - tmp);
        while (tt % 3 == 0) tt /= 3;
        if (tt < 3)
            printf("%d", ans), exit(0);
    }
}