BigNumber_1

A - BigNumber_1

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u

Submit Status

Description

A Fibonacci sequence is calculated by adding the previous two members the sequence, with the first two members being both 1. 
F(1) = 1, F(2) = 1, F(3) = 1,F(4) = 1, F(n>4) = F(n - 1) + F(n-2) + F(n-3) + F(n-4) 
Your task is to take a number as input, and print that Fibonacci number. 

 

Input

Each line will contain an integers. Process to end of file. 

 

Output

For each case, output the result in a line.

 

Sample Input

100 

 

Sample Output

4203968145672990846840663646Note:No generated Fibonacci number in excess of 2005 digits will be in the test data, ie. F(20) = 66526 has 5 digits.                

 

PS：大数相加+斐波那契数列

代码：

#include<iostream>#include<string>using namespace std;int ns[2100] = { 0 };string add(string sa, string sb){string sa1, sb1;sa1 = sa;sb1 = sb;int la = sa.length();int lb = sb.length();if (la < lb){string tmps = sa;sa = sb;sb = tmps;int tmpi;tmpi = la;la = lb;lb = tmpi;}string st = "";for (int j = lb; j < la; ++j){st += '0';}st += sb;sb = st;int num = 0, k = 0;for (int m = la - 1; m >= 0; --m){int sum = (sa[m] - '0') + (sb[m] - '0') + num;ns[k++] = sum % 10;num = sum / 10;}if (num > 0){ns[k++] = num;}string str = "";for (int j = k - 1; j >= 0; --j){str += (ns[j] + '0');}return str;}int main(){string f[7101];f[1] = f[2] = f[3] = f[4] = "1";for (int i = 5; i < 7101; ++i){f[i] = add(add(f[i - 1], f[i - 2]), add(f[i - 3], f[i - 4]));}int num;while (cin >> num){cout << f[num] << endl;//cout << f[num].length() << endl;}return 0;}