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| class BigInt {
public:
string value;
BigInt(string s) { value = s; };
BigInt() { value = "0"; };
friend BigInt operator-(BigInt a, BigInt b) {
return BigInt(a.sub(a.value, b.value));
}
friend BigInt operator+(BigInt a, BigInt b) {
return BigInt(a.add(a.value, b.value));
}
friend BigInt operator/(BigInt a, BigInt b) {
return BigInt(a.div(a.value, b.value));
}
friend BigInt operator*(BigInt a, BigInt b) {
return BigInt(a.mul(a.value, b.value));
}
BigInt& operator+=(BigInt b) {
value = add(value, b.value);
return *this;
}
BigInt& operator-=(BigInt b) {
value = sub(value, b.value);
return *this;
}
BigInt& operator*=(BigInt b) {
value = mul(value, b.value);
return *this;
}
BigInt& operator/=(BigInt b) {
value = div(value, b.value);
return *this;
}
private:
string add(string a, string b) {
bool neg = false;
if (a[0] == '+') a = a.substr(1);
if (b[0] == '+') b = b.substr(1);
if (a[0] == '-' && b[0] == '-') {
neg = true;
a = a.substr(1);
b = b.substr(1);
} else if (a[0] == '-' && b[0] != '-')
return sub(b, a.substr(1));
else if (a[0] != '-' && b[0] == '-')
return sub(a, b.substr(1));
ull maxlen = max(a.size(), b.size());
ull l = 0, r = a.size() - 1;
string ans(maxlen + 1, '0');
while (l < r) {
swap(a[l], a[r]);
l++, r--;
}
l = 0, r = b.size() - 1;
while (l < r) {
swap(b[l], b[r]);
l++, r--;
}
a += string(maxlen - a.size(), '0');
b += string(maxlen - b.size(), '0');
for (ull i = 0; i < maxlen; ++i) {
ans[i + 1] = (ans[i] - '0' + a[i] - '0' + b[i] - '0') / 10 + '0';
ans[i] = (ans[i] - '0' + a[i] - '0' + b[i] - '0') % 10 + '0';
}
r = maxlen;
while (r > 0 && ans[r] == '0') r--;
ans = ans.substr(0, r + 1);
l = 0;
while (l < r) {
swap(ans[l], ans[r]);
l++, r--;
}
return neg ? "-" + ans : ans;
}
string sub(string a, string b) {
bool neg = false;
if (a[0] == '+') a = a.substr(1);
if (b[0] == '+') b = b.substr(1);
if (b[0] == '-') return add(a, b.substr(1));
if (a[0] == '-') return "-" + add(a.substr(1), b);
if (a.size() < b.size() || (a.size() == b.size() && a < b)) {
neg = true, swap(a, b);
}
ull maxlen = max(a.size(), b.size());
ull l = 0, r = a.size() - 1;
while (l < r) {
swap(a[l], a[r]);
l++, r--;
}
l = 0, r = b.size() - 1;
while (l < r) {
swap(b[l], b[r]);
l++, r--;
}
a += string(maxlen - a.size(), '0');
b += string(maxlen - b.size(), '0');
string ans = a;
for (ull i = 0; i < maxlen; ++i) {
ans[i + 1] -= ans[i] >= b[i] ? 0 : 1;
ans[i] = (ans[i] - b[i] + 10) % 10 + '0';
}
r = maxlen - 1;
while (r > 0 && ans[r] == '0') r--;
ans = ans.substr(0, r + 1);
l = 0;
while (l < r) {
swap(ans[l], ans[r]);
l++, r--;
}
return neg ? "-" + ans : ans;
}
string mul(string a, string b) {
bool neg = false;
if (a[0] == '+') a = a.substr(1);
if (b[0] == '+') b = b.substr(1);
if (a[0] == '-' && b[0] != '-') {
neg = true;
a = a.substr(1);
} else if (a[0] != '-' && b[0] == '-') {
neg = true;
b = b.substr(1);
} else if (a[0] == '-' && a[0] == b[0]) {
a = a.substr(1);
b = b.substr(1);
}
ull maxlen = max(a.size(), b.size());
ull l = 0, r = a.size() - 1;
string ans(maxlen * 2, '0');
while (l < r) {
swap(a[l], a[r]);
l++, r--;
}
l = 0, r = b.size() - 1;
while (l < r) {
swap(b[l], b[r]);
l++, r--;
}
if (a.size() < b.size()) swap(a, b);
for (ull i = 0; i < b.size(); ++i) {
for (ull j = 0; j < a.size(); ++j) {
ans[i + j + 1] += (a[j] - '0') * (b[i] - '0') / 10;
ans[i + j] = (a[j] - '0') * (b[i] - '0') % 10 + '0';
}
}
r = maxlen;
while (r > 0 && ans[r] == '0') r--;
ans = ans.substr(0, r + 1);
l = 0;
while (l < r) {
swap(ans[l], ans[r]);
l++, r--;
}
return neg ? "-" + ans : ans;
}
string div(string a, string b) {
bool neg = false;
if (a[0] == '+') a = a.substr(1);
if (b[0] == '+') b = b.substr(1);
if (a[0] == '-' && b[0] != '-') {
neg = true;
a = a.substr(1);
} else if (a[0] != '-' && b[0] == '-') {
neg = true;
b = b.substr(1);
} else if (a[0] == '-' && a[0] == b[0]) {
a = a.substr(1);
b = b.substr(1);
}
string ans;
if (a.size() < b.size())
ans = "0";
else {
string remain = a.substr(0, b.size() - 1), temp;
for (ull i = b.size() - 1; i < a.size(); ++i) {
remain += a[i];
if (remain.size() >= b.size() && remain >= b) {
for (int t = '9'; t > '0'; --t) {
if ((temp = mul(b, string(1, t))) <= remain &&
temp.size() <= remain.size()) {
ans += t;
remain = sub(remain, temp);
break;
}
}
}
}
}
return neg ? "-" + ans : ans;
}
};
|