NKTOSS - Tung đồng xu
Tác giả: ladpro98
Ngôn ngữ: C++
#include <bits/stdc++.h>
const int MOD = 100000000;
using namespace std;
typedef vector<int> big;
int n, k;
big F[10005];
big operator + (const big &a, const big &b) {
big c; int carry = 0;
for(int i = 0; i < a.size() || i < b.size(); i++) {
if (i < a.size()) carry += a[i];
if (i < b.size()) carry += b[i];
c.push_back(carry % MOD);
carry /= MOD;
}
if (carry) c.push_back(carry);
return c;
}
big operator - (const big &a, const big &b) {
big c; int borrow = 0, s;
for(int i = 0; i < a.size(); i++) {
s = a[i] - borrow;
if (i < b.size()) s -= b[i];
if (s < 0) {
s += MOD;
borrow = 1;
}
else
borrow = 0;
c.push_back(s);
}
while (!c.empty() && c[c.size() - 1] == 0) c.pop_back();
return c;
}
void print(big a) {
printf("%d", a[a.size() - 1]);
for(int i = a.size() - 2; i >= 0; i--)
printf("%08d", a[i]);
printf("\n");
}
int main() {
scanf("%d %d", &n, &k);
F[0].push_back(1);
big prev; prev.push_back(1);
big POW; POW.push_back(1);
for(int i = 1; i <= n + 1; i++) {
F[i] = prev;
prev = prev + F[i];
if (i >= k)
prev = prev - F[i - k];
if (i <= n)
POW = POW + POW;
}
print(POW - F[n + 1]);
return 0;
}