Question

Original page: http://acm.whu.edu.cn/learn/problem/detail?problem_id=1036

This should be a simple Dynamic Programming problem. I figured out the solution to be the following:

int main(void)
{
    double d[501];
    int i;
    d[0] = d[1] = 1.;
    d[2] = 2.;
    for(i = 3; i<=500; i++)
        d[i] = d[i-1] + d[i-2] + d[i-3];


    int n;
    while(scanf("%d", &n) == 1) {
        if(n == 0) return 0;
        printf("%.0lf\n", d[n]);
    }

    return 0;
}

But Wrong Answer reported after submission. I really don’t know why.

Answer 1

double is not enough for the precision

you should use high-precision to solve it