HDU 1056 叠木块 程序效率低，怎么优化？

#include <iostream>using namespace std;int main(){double a[300];a[0] = 0;for(int i = 1; i < 300; i++){a[i] = a[i-1] + 1.0 /(i + 1);}double len;while(cin >> len, len){int cnt = 0;for(int i = 1; i < 300; i++){if(a[i] >= len && a[i-1] < len){cnt = i;break;}}cout << cnt << " card(s)" << endl;}return 0;}