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| #include <bits/stdc++.h>
#define mod (int)(1e9 + 7)
#define int long long
#define endl '\n'
#define pb push_back
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define fst first
#define snd second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const int MAX = INT_MAX;
const ll LLMAX = LONG_LONG_MAX;
const double PI = acos(-1);
using namespace std;
class BigInt {
private:
string value;
static map<int, string> digitToString;
string add(string a, string b);
string sub(string a, string b);
string mul(string a, string b);
string div(string a, string b);
public:
BigInt() : value("0") {}
BigInt(ll x) {
while (x) {
value = digitToString[(int)x % 10] + value;
x /= 10;
}
}
BigInt(string number) : value(number) {}
BigInt(string& number) : value(number) {}
BigInt(const BigInt& number) : value(number.value) {}
friend ostream& operator<<(ostream& output, const BigInt& x) {
return cout << x.value;
}
BigInt operator+(const BigInt& b) { return BigInt(add(value, b.value)); }
BigInt operator-(const BigInt& b) { return BigInt(sub(value, b.value)); }
BigInt operator/(const BigInt& b) { return BigInt(div(value, b.value)); }
BigInt operator*(const BigInt& b) { return BigInt(mul(value, b.value)); }
BigInt& operator=(const BigInt& x) {
value = x.value;
return *this;
}
BigInt& operator=(const string& number) {
value = number;
return *this;
}
};
string BigInt::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()), r = a.size() - 1;
string ans(maxlen + 1, '0');
if (a.size() > b.size())
b.insert(0, a.size() - b.size(), '0');
else
a.insert(0, b.size() - a.size(), '0');
reverse(a.begin(), a.end());
reverse(b.begin(), b.end());
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);
reverse(ans.begin(), ans.end());
return neg ? "-" + ans : ans;
}
string BigInt::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()), r = a.size() - 1;
b.insert(0, a.size() - b.size(), '0');
reverse(a.begin(), a.end());
reverse(b.begin(), b.end());
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);
reverse(ans.begin(), ans.end());
return neg ? "-" + ans : ans;
}
string BigInt::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 r = a.size() - 1;
string ans(maxlen * 2, '0');
reverse(a.begin(), a.end());
reverse(b.begin(), b.end());
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] += (ans[i + j] - '0' + (a[j] - '0') * (b[i] - '0')) / 10;
ans[i + j] = (ans[i + j] - '0' + (a[j] - '0') * (b[i] - '0')) % 10 + '0';
}
r = 2 * maxlen - 1;
while (r > 0 && ans[r] == '0') r--;
ans = ans.substr(0, r + 1);
reverse(ans.begin(), ans.end());
return neg && ans != "0" ? "-" + ans : ans;
}
string BigInt::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], remain = mul(remain, "1");
if (remain.size() > b.size() ||
(remain.size() == b.size() && remain >= b))
for (char t = '9'; t >= '0'; --t) {
temp = mul(b, string(1, t));
if (temp.size() < remain.size() ||
(temp.size() == remain.size() && temp <= remain)) {
ans += t, remain = sub(remain, temp);
break;
}
}
else
ans += '0';
}
}
if (ans != "0") {
int i = 0;
while (ans[i] == '0') i++;
ans = ans.substr(i);
}
return neg && ans != "0" ? "-" + ans : ans;
}
map<int, string> BigInt::digitToString = {
{1, "1"}, {2, "2"}, {3, "3"}, {4, "4"}, {5, "5"},
{6, "6"}, {7, "7"}, {8, "8"}, {9, "9"}, {0, "0"}};
void solve() {
int n;
cin >> n;
vector<BigInt> dp(n + 1);
dp[0] = dp[1] = "1";
for (int i = 2; i <= n; i++) {
dp[i] = dp[i - 1] + dp[i - 2];
}
cout << dp[n] << endl;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t = 1;
while (t--) solve();
return 0;
}
|