bigint::bigvalue_t do_bigadd(const bigint::bigvalue_t& left,
const bigint::bigvalue_t& right) {
bigint::bigvalue_t sum;
int carry = 0;
bool left_empty = false;
bool right_empty = false;
auto left_it = left.begin();
//bigint::bigvalue_t::const_reverse_iterator left_it = left.rbegin();
auto right_it = right.begin();
auto left_end = left.end();
auto right_end = right.end();
if(left.size() == 0) {
left_empty = true;
}
if(right.size() == 0) {
right_empty = true;
}
while(true) {
int curr_value = (left_empty?0:*left_it) +
(right_empty?0:*right_it) + carry;
carry = 0;
if(curr_value >= 10) {
carry = 1;
curr_value -= 10;
}
sum.push_back(curr_value);
if(++left_it == left_end) {
left_empty = true;
}
if(++right_it == right_end) {
right_empty = true;
}
if(left_empty and right_empty) {
if(carry == 1) {
sum.push_back(carry);
}
break;
}
}
return sum;
}
bigint::bigvalue_t do_bigsub(const bigint::bigvalue_t& left,
const bigint::bigvalue_t& right) {
bigint::bigvalue_t sum;
int carry = 0;
bool left_empty = false;
bool right_empty = false;
auto left_it = left.begin();
//bigint::bigvalue_t::const_reverse_iterator left_it = left.rbegin();
auto right_it = right.begin();
auto left_end = left.end();
auto right_end = right.end();
if(left.size() == 0) {
left_empty = true;
}
if(right.size() == 0) {
right_empty = true;
}
while(true) {
int curr_value = (left_empty?0:*left_it) -
(right_empty?0:*right_it) + carry;
carry = 0;
if(curr_value < 0 and !left_empty) {
carry = -1;
curr_value += 10;
}
sum.push_back(curr_value);
if(++left_it == left_end) {
left_empty = true;
}
if(++right_it == right_end) {
right_empty = true;
}
if(left_empty and right_empty) {
break;
}
}
//remove leading 0s
sum = trim(sum);
return sum;
}
//
// do_bigless()
// returns true if left < right
// returns false if left > right or left == right
//
bool do_bigless (const bigint::bigvalue_t& left,
const bigint::bigvalue_t& right) {
if (left.size() < right.size()) {
return true;
} else if (left.size() > right.size()) {
return false;
}
auto itor_left = left.begin();
auto itor_right = right.begin();
while(itor_left != left.end() && itor_right != right.end()) {
if (itor_left > itor_left) {
return false;
} else if (itor_left < itor_right) {
return true;
} else {
itor_left++;
itor_right++;
}
}
return true;
}