hdoj 1041 Computer Tranformation

找规律+大数加法,?

a[i] = a[i-2] + a[i-1];

/*
PROG: Computer Transformation
LANG: C++11 
*/
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <cstdlib>
#include <climits>
#include <ctype.h>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <deque>
#include <set>
#include <map>
#include <iostream>
#include <algorithm>
#include <fstream>

using namespace std;

#define mst(a,b) memset(a,b,sizeof(a));

typedef long long ll;
const int maxn = 200100;
const ll mod = 1000000007;

void pplus(vector<int> &a,vector<int> &b,vector<int> &ans){
    int m = a.size(); int n = b.size();
    int carry = 0;
    int d1,d2;
    for(int i = 0,j = 0; i < m || j < n|| carry; i++,j++){
        d1 = i < m ? a[i] : 0;
        d2 = j < n ? b[j] : 0;
        carry = d1 + d2 + carry;
        ans.push_back(carry%10);
        carry /= 10;
    }
}

vector<int> a[1001];

int main()
{
    a[1].push_back(0);
    a[2].push_back(1);
    a[3].push_back(1);
    for(int i = 4; i <= 1000; i++){
        vector<int> temp;
        pplus(a[i-2],a[i-2],temp);
        pplus(temp,a[i-1],a[i]);
    }
    int n;

    while(scanf("%d",&n) != EOF){
        for(int j = a[n].size()-1; j>= 0; j--){
            cout << a[n][j];
        }
        cout << endl;
    }
    return 0;
}