HDU 1250 Hat's Fibonacci（大数相加）

传送门：http://acm.hdu.edu.cn/showproblem.php?pid=1250

Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12952    Accepted Submission(s): 4331

Problem 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

4203968145672990846840663646

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

Author

戴帽子的

分析：

大数相加的模板题！

code：

#include<bits/stdc++.h>
using namespace std;
#define max_v 10005

string add(string s1,string s2)

{

    if(s1.length()<s2.length())

    {

        string temp=s1;

        s1=s2;

        s2=temp;

    }

    int i,j;

    for(i=s1.length()-,j=s2.length()-;i>=;i--,j--)

    {

        s1[i]=char(s1[i]+(j>=?s2[j]-'':));   //注意细节

        if(s1[i]-''>=)

        {

            s1[i]=char((s1[i]-'')%+'');

            if(i) s1[i-]++;

            else s1=''+s1;

        }

    }

    return s1;

}

int main()
{
    int n;
    while(~scanf("%d",&n))
    {
        string p[n+];
        if(n<=)
        {
            printf("1\n");
            continue;
        }
        p[]="";
        p[]="";
        p[]="";
        p[]="";
        for(int i=; i<=n; i++)
        {
            p[i]=add(p[i-],add(p[i-],add(p[i-],p[i-])));
        }
        cout<<p[n]<<endl;
    }
    return ;
}