void swap_v1(int* val_1, int* val_2)
{
    int temp = *val_1;
    *val_1 = *val_2;
    *val_2 = *val_1;
}

#define SWAP_V2(a, b) (a += b, b = a - b, a -= b)
#define SWAP_V3(x, y) {x ^= y; y ^= x; x ^= y}

static inline void swap_final(int* val_1, int* val_2)
{
    if(val_1 == val_2)
        return;
    *val_1 ^= *val_2;
    *val_2 ^= *val_1;
    *val_1 ^= *val_2;
}
#define SWAP(x, y) \
do{                    \
    if(&x == &y)    \
        break;         \
    x ^= y;        \
    y ^= x;        \
    x ^= y;        \
}while(0)