代码

#ifndef DUCK_FASTIO_H
#define DUCK_FASTIO_H

typedef unsigned long duck_u64;
typedef long duck_i64;

typedef struct {
    duck_u64 abi_version;
    const char *stdin_ptr;
    duck_u64 stdin_size;
    char *stdout_ptr;
    duck_u64 stdout_limit;
    duck_u64 stdout_size;
    char *stderr_ptr;
    duck_u64 stderr_limit;
    duck_u64 stderr_size;
    const char *ib_ptr;
    duck_u64 ib_limit;
    char *ob_ptr;
    duck_u64 ob_limit;
    duck_u64 tsc_frequency;
} __attribute__((packed)) DuckInfo;

static __attribute__((always_inline)) inline DuckInfo *duck_info(long argc, char **argv) {
    char **p = argv + argc + 1;
    while (*p) ++p;
    duck_u64 *aux = (duck_u64 *)(p + 1);
    while (aux[0]) {
        if (aux[0] == 0x6b637564UL) return (DuckInfo *)aux[1];
        aux += 2;
    }
    return (DuckInfo *)0;
}

static __attribute__((always_inline)) inline duck_u64 duck_read_u64(const char **cursor) {
    const char *p = *cursor;
    while ((unsigned char)(*p - '0') > 9) ++p;
    duck_u64 value = 0;
    do {
        value = value * 10 + (unsigned char)(*p - '0');
        ++p;
    } while ((unsigned char)(*p - '0') <= 9);
    *cursor = p;
    return value;
}

static __attribute__((always_inline)) inline duck_i64 duck_read_i64(const char **cursor) {
    const char *p = *cursor;
    while (*p != '-' && (unsigned char)(*p - '0') > 9) ++p;
    int negative = *p == '-';
    p += negative;
    duck_u64 value = 0;
    do {
        value = value * 10 + (unsigned char)(*p - '0');
        ++p;
    } while ((unsigned char)(*p - '0') <= 9);
    *cursor = p;
    return negative ? -(duck_i64)value : (duck_i64)value;
}

static __attribute__((always_inline)) inline char *duck_write_u64(char *out, duck_u64 value) {
    char tmp[24];
    unsigned n = 0;
    do {
        tmp[n++] = (char)('0' + value % 10);
        value /= 10;
    } while (value);
    do *out++ = tmp[--n]; while (n);
    return out;
}

static __attribute__((always_inline)) inline char *duck_write_i64(char *out, duck_i64 value) {
    if (value < 0) {
        *out++ = '-';
        return duck_write_u64(out, (duck_u64)(-value));
    }
    return duck_write_u64(out, (duck_u64)value);
}

static __attribute__((always_inline, noreturn)) inline void duck_exit(void) {
    __asm__ volatile("mov $60,%%eax;xor %%edi,%%edi;syscall" ::: "rax", "rdi", "rcx", "r11", "memory");
    __builtin_unreachable();
}

#endif


typedef unsigned int u32;

static __attribute__((always_inline)) inline u32 mul_mod(u32 a, u32 b) {
    return (u32)((duck_u64)a * b % 1000000007u);
}

static __attribute__((always_inline)) inline u32 pow_mod(u32 a, u32 e) {
    u32 r = 1;
    while (e) {
        if (e & 1) r = mul_mod(r, a);
        a = mul_mod(a, a);
        e >>= 1;
    }
    return r;
}

__attribute__((noreturn))
void __libc_start_main(void *unused, long argc, char **argv) {
    (void)unused;
    DuckInfo *info = duck_info(argc, argv);
    const char *p = info->stdin_ptr;
    u32 n = (u32)duck_read_u64(&p);
    u32 m = (u32)duck_read_u64(&p);
    if (n > m) {
        u32 t = n;
        n = m;
        m = t;
    }

    u32 answer;
    if (n == 1) {
        answer = pow_mod(2, m);
    } else if (n == 2) {
        answer = mul_mod(4, pow_mod(3, m - 1));
    } else if (n == 3) {
        answer = mul_mod(112, pow_mod(3, m - 3));
    } else {
        static const u32 square[9] = {
            0, 0, 0, 0, 912, 7136, 56768, 453504, 3626752
        };
        static const u32 next_column[9] = {
            0, 0, 0, 0, 2688, 21312, 170112, 1360128, 10879488
        };
        if (m == n) {
            answer = square[n];
        } else {
            answer = mul_mod(next_column[n], pow_mod(3, m - n - 1));
        }
    }

    char *out = info->stdout_ptr;
    out = duck_write_u64(out, answer);
    *out++ = '\n';
    info->stdout_size = (duck_u64)(out - info->stdout_ptr);
    duck_exit();
}

int main(void) {}

评测结果