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Fibonacci.cpp
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Fibonacci.cpp
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#include <iostream>
#include <chrono>
#include <limits>
using namespace std::chrono;
using namespace std;
long long fib1(int n) {
if (n <= 1) {
return n;
}
else {
return fib1(n - 1) + fib1(n - 2);
}
}
long long fib2(int n, long long* arr) {
arr[0] = 0;
arr[1] = 1;
for (int i = 2; i <= n; i++) {
arr[i] = arr[i - 1] + arr[i - 2];
if (arr[i] < arr[i - 1]) {
cout << "Overflow detected at position " << i << endl;
return -1;
}
}
return arr[n];
}
int main() {
int n;
cout << "Enter the position for the Fibonacci number: ";
cin >> n;
if (n < 0) {
cout << "Please enter a non-negative number" << endl;
return 1;
}
long long* arr = new (nothrow) long long[n + 1];
if (arr == nullptr) {
cout << "Memory allocation failed" << endl;
return 1;
}
auto start = high_resolution_clock::now();
long long f1 = -1;
if (n <= 40) {
f1 = fib1(n);
}
else {
cout << "Skipping recursive calculation for n > 40 to avoid excessive computation time." << endl;
}
auto end = high_resolution_clock::now();
auto duration1 = duration_cast<milliseconds>(end - start);
auto start1 = high_resolution_clock::now();
long long f2 = fib2(n, arr);
auto end1 = high_resolution_clock::now();
auto duration2 = duration_cast<milliseconds>(end1 - start1);
if (f1 != -1) {
cout << "Fibonacci number (recursive) is: " << f1 << endl;
cout << "It takes time " << duration1.count() << " milliseconds" << endl;
}
if (f2 != -1) {
cout << "Fibonacci number (iterative) is: " << f2 << endl;
cout << "It takes time " << duration2.count() << " milliseconds" << endl;
}
else {
cout << "Iterative method failed due to overflow." << endl;
}
delete[] arr;
}