Fibonacci Modified


Problem Statement :


Implement a modified Fibonacci sequence using the following definition:

Given terms t[i] and t[i+1] where i ∈ (1,∞), term t[i+2] is computed as:
t(i+2) = ti + t(i+2)^2

Given three integers, t1, t2, and n, compute and print the nth term of a modified Fibonacci sequence.

Example
t1 = 0
t2 =0
n =6

  t3 = 0+1^2 = 1
  t4 = 1+1^2 = 2
  t5 = 1+2^2 = 5
  t6 = 2+5^2 = 27
Return 27.

Function Description

Complete the fibonacciModified function in the editor below. It must return the nth number in the sequence.

fibonacciModified has the following parameter(s):

int t1: an integer
int t2: an integer
int n: the iteration to report

Returns

int: the nth number in the sequence
Note: The value of t[n] may far exceed the range of a 64-bit integer. Many submission languages have libraries that can handle such large results but, for those that don't (e.g., C++), you will need to compensate for the size of the result.

Input Format

A single line of three space-separated integers, the values of t1, t2, and n.

Constraints

0 <= t1, t2 <= 2
3 <= n <= 20
tn may far exceed the range of a 64-bit integer.



Solution :



title-img


                            Solution in C :

In C++ :






#include <iostream>
#include <utility>

#include <boost/multiprecision/cpp_int.hpp>

using boost::multiprecision::cpp_int;

cpp_int fib(cpp_int a, cpp_int b, unsigned int n)
{
    for(unsigned int i = 2; i < n; ++i)
    {
        cpp_int temp = a + b*b;
        a = b;
        b = temp;
    }
    return b;
}

int main()
{
    unsigned int a, b, n;

    std::cin >> a >> b >> n;
    std::cout << fib(a, b, n);
}








In Java :






import java.math.BigInteger;
import java.util.Scanner;


public class Solution {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		BigInteger a = BigInteger.valueOf(in.nextInt());
		BigInteger b = BigInteger.valueOf(in.nextInt());
		int n = in.nextInt();
		for(int i = 2; i < n; i++) {
			BigInteger next = b.multiply(b).add(a);
			a = b;
			b = next;
		}
		System.out.println(b);
	}
}








In C :






#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

#define MAXL    26624

unsigned int MADD(unsigned int* pC, unsigned int* pB, unsigned int* pA, unsigned int n)
{
    unsigned int i,j,x;
    
    for (i=0; i<n; i++) pC[i] = pA[i];
    for (i=0; i<n; i++)
    {
        for (j=0; j<n; j++)
        {
            if ((x = (pC[i+j] += pB[i]*pB[j])) < 10000) continue;
            x /= 10000; pC[i+j+1] += x; pC[i+j] -= x*10000;            
        }
        if ((x = pC[i+j]) < 10000) continue;
        x /= 10000; pC[i+j+1] += x; pC[i+j] -= x*10000;            
    }
    n <<= 1; while (pC[n-1] == 0) n--;
    return n;
}

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    unsigned int N,m,n=1;
    unsigned int* p;
    unsigned int* pA;
    unsigned int* pB;
    unsigned int* pC;
    unsigned int A[MAXL];
    unsigned int B[MAXL];
    unsigned int C[MAXL];

    memset(pA=A, 0, sizeof(A));
    memset(pB=B, 0, sizeof(B));
    memset(pC=C, 0, sizeof(C));

    scanf("%d %d %d\n", pA, pB, &N);

    while (N-- > 2)
    {
        n = MADD(pC, pB, pA, n);
        p = pC; pC=pA; pA = pB; pB=p;
    }
    printf("%d", p[--n]);
    while (n > 0) printf("%04u", p[--n]);
    printf("\n");
    return 0;
}








In Python3 :






a, b, n = [int(x) for x in input().split(" ")]

if n == 0:
    print(a)
if n == 1:
    print(b)

for _ in range(n-2):
    a, b = b, b*b + a
    
print(b)
                        








View More Similar Problems

Mr. X and His Shots

A cricket match is going to be held. The field is represented by a 1D plane. A cricketer, Mr. X has N favorite shots. Each shot has a particular range. The range of the ith shot is from Ai to Bi. That means his favorite shot can be anywhere in this range. Each player on the opposite team can field only in a particular range. Player i can field from Ci to Di. You are given the N favorite shots of M

View Solution →

Jim and the Skyscrapers

Jim has invented a new flying object called HZ42. HZ42 is like a broom and can only fly horizontally, independent of the environment. One day, Jim started his flight from Dubai's highest skyscraper, traveled some distance and landed on another skyscraper of same height! So much fun! But unfortunately, new skyscrapers have been built recently. Let us describe the problem in one dimensional space

View Solution →

Palindromic Subsets

Consider a lowercase English alphabetic letter character denoted by c. A shift operation on some c turns it into the next letter in the alphabet. For example, and ,shift(a) = b , shift(e) = f, shift(z) = a . Given a zero-indexed string, s, of n lowercase letters, perform q queries on s where each query takes one of the following two forms: 1 i j t: All letters in the inclusive range from i t

View Solution →

Counting On a Tree

Taylor loves trees, and this new challenge has him stumped! Consider a tree, t, consisting of n nodes. Each node is numbered from 1 to n, and each node i has an integer, ci, attached to it. A query on tree t takes the form w x y z. To process a query, you must print the count of ordered pairs of integers ( i , j ) such that the following four conditions are all satisfied: the path from n

View Solution →

Polynomial Division

Consider a sequence, c0, c1, . . . , cn-1 , and a polynomial of degree 1 defined as Q(x ) = a * x + b. You must perform q queries on the sequence, where each query is one of the following two types: 1 i x: Replace ci with x. 2 l r: Consider the polynomial and determine whether is divisible by over the field , where . In other words, check if there exists a polynomial with integer coefficie

View Solution →

Costly Intervals

Given an array, your goal is to find, for each element, the largest subarray containing it whose cost is at least k. Specifically, let A = [A1, A2, . . . , An ] be an array of length n, and let be the subarray from index l to index r. Also, Let MAX( l, r ) be the largest number in Al. . . r. Let MIN( l, r ) be the smallest number in Al . . .r . Let OR( l , r ) be the bitwise OR of the

View Solution →