Function swap

contents/huffman_encoding/code/c/huffman.c:34–38

}

void swap(struct tree** lhs, struct tree** rhs) {
    struct tree* tmp = *lhs;
    *lhs = *rhs;
    *rhs = tmp;
}

/* The two concat functions are horribly inefficient */
void concat(char** dst, const char* src) {