ZOJ Problem Set–1828 Fibonacci Numbers

Time Limit: 2 Seconds      Memory Limit: 65536 KBA Fibonacci sequence is calculated by adding the previous two members of the sequence, with the first two members being both 1. f(1) = 1, f(2) = 1, f(n > 2) = f(n - 1) + f(n - 2)Your task is to take a number as input, and print that Fibonacci number.Sample Input100Sample Output354224848179261915075Note:No generated Fibonacci number in excess of 1000 digits will be in the test data, i.e. f(20) = 6765 has 4 digits.Source: University of Waterloo Local Contest 1996.10.05

#include<iostream>

#include<vector>

#include<string>

using namespace std;

const short NUMLENGTH = 1001;

class BigInteger

{

private:

unsigned short *num;

size_t size;

BigInteger& addBigInteger(const BigInteger& pre1, const BigInteger& pre2) const

  {

BigInteger *result = new BigInteger();

size_t loop = pre1.size > pre2.size ? pre1.size:pre2.size;

bool carry = false;//标记运算是否有进位

short tempResult;

size_t i = 0;

for(i = 0; i < loop; i++)

    {

tempResult = *(pre1.num + i)*(i < pre1.size) + *(pre2.num + i)*(i < pre2.size) + (short)carry;

carry = (tempResult >= 10);

*(result->num + i) = tempResult - 10*carry;

}

*(result->num + i) = (short)carry;

result->size = loop + (int)carry;

return *result;

}

public:

BigInteger()

  {

num = new unsigned short[NUMLENGTH];

for(int i = 0; i < NUMLENGTH; i++)

*(this->num + i) = 0;

size = 0;

}

BigInteger(const BigInteger& bi)

  {

num = new unsigned short[NUMLENGTH];

this->size = bi.size;

for(int i = 0; i < NUMLENGTH;i++)

*(this->num + i) = *(bi.num + i);

}

BigInteger(const string& bi)

  {

this->size = bi.length();

num = new unsigned short[NUMLENGTH];

for(int i = size - 1; i >= 0; i--)

    {

*(this->num + i) = bi[i] - '0';

}

for(int j = size; j < NUMLENGTH; j++)

    {

*(this->num + j) = 0;

}

}

BigInteger& operator+(const BigInteger& op) const

  {

return addBigInteger(*this, op);

}

  void printInteger()

  {

for(int i = size - 1; i >= 0; i--)

      cout<<*(num + i);

}

  void printDataArr()

  {

for(int i = 0; i < NUMLENGTH; i++)

      cout<<*(num + i);

}

  ~BigInteger()

  {

    delete [] num;

}

};

int main(void)

{

  vector<BigInteger> fabonacci;

  fabonacci.push_back(BigInteger("0"));

  fabonacci.push_back(BigInteger("1"));

  fabonacci.push_back(BigInteger("1"));

  int num;

  while(cin>>num)

  {

    if(fabonacci.size() <= num)

    {

      for(int i = fabonacci.size() - 1;i < num; i++)

        fabonacci.push_back(fabonacci[i] + fabonacci[i - 1]);

}

    fabonacci[num].printInteger();

    cout<<endl;

}

  return 0;

}