hdu Children’s Queue

http://acm.hdu.edu.cn/game/entry/problem/show.php?chapterid=3&sectionid=1&problemid=10

#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 300000
using namespace std;

int n;
int a[1001][500];

void inti()
{
    a[1][0]=1;
    a[2][0]=2;
    a[3][0]=4;
    a[4][0]=7;
    for(int i=5; i<=1000; i++)
    {
        int c=0;
        for(int j=0; j<=300; j++)
        {
            a[i][j]=a[i-1][j]+a[i-2][j]+a[i-4][j]+c;
            c=a[i][j]/10;
            a[i][j]%=10;
        }
    }
}

int main()
{
    inti();
    while(scanf("%d",&n)!=EOF)
    {
        int i=4a99;
        while(i>=0&&!a[n][i]) i--;
        while(i>=0)
        {
            printf("%d",a[n][i]);
            i--;
        }
        printf("
");
    }
    return 0;
}