HDU - 1041 Computer Transformation

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <algorithm>
using namespace std;

int a[1005][1001] = {0}; //  假设每个都是1000位的大数 下标1表个位，2表十位...

//F(n) = F(n - 2) + 2 ^ (n - 3);
void deal()  //  提前打表
{
    a[0][1] = 1;     //    表示2^(n-3)
    a[1][1] = 0, a[2][1] = 1, a[3][1] = 1; //  第 1，2，3步的答案
    for (int i = 4; i <= 1000; i++)    //   计算第4-1000步的答案
    {
        int r = 0;
        for (int j = 1; j <= 1000; j++)  //   计算2^（n-3）
        {
            a[0][j] *= 2;
            a[0][j] += r;
            r = 0;
            if (a[0][j] > 9)
            {
                r = 1;
                a[0][j] -= 10;
            }
        }
        r = 0;
        for (int j = 1; j <= 1000; j++) // 计算F(n) = F(n - 2) + 2 ^ (n - 3);
        {
            a[i][j] = a[i - 2][j] + a[0][j] + r;;
            r = 0;
            if (a[i][j] > 9)
            {
                r = 1;
                a[i][j] -= 10;
            }
        }
    }
}
int main()
{
    deal();
    int n;
    while (cin >> n)
    {
        if (n == 1)
        {
            cout << 0 << endl;
            continue;
        }
        int i = 1000;
        while (a[n][i] == 0)i--;
        for (; i >= 1; i--)
            printf("%d", a[n][i] );
        printf("\n");
    }
}