P1255 数楼梯

题目链接：P1255 数楼梯 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

#include <iostream>
using namespace std;
int a[5010][5010];

int main() {
	a[0][0] = 1;
	a[1][0] = 1;
	int n;
	cin >> n;
	if (n == 0) {
		cout << 0;
	} else {
		for (int i = 2; i <= n; i++) {
			//a[i]=a[i-1]+a[i-2]; 高精加
			int x, y;
			for (int j = 0; j < 1500; j++) {
				a[i][j] += a[i - 1][j] + a[i - 2][j];
				int index = j;
				while (a[i][index] >= 10) {
					a[i][index + 1] += a[i][index] / 10;
					a[i][index] %= 10;
					index++;
				}
			}
		}
		bool flag = 0;
		for (int i = 1500; i >= 0; i--) {
			if (a[n][i] != 0) {
				flag = 1;
			}
			if (flag == 1) {
				cout << a[n][i];
			}
		}
	}
	return 0;
}