题解 | #N阶楼梯上楼问题#

//土尔逊Torson 编写于2023/10/08
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>

using namespace std;

const int MAXN145 = 90;

long long dp145[MAXN145];

int main() {
	dp145[0] = 0;
	dp145[1] = 1;
	dp145[2] = 2;
	for (int i = 3; i < MAXN145; ++i) {
		dp145[i] = dp145[i - 1] + dp145[i - 2];
	}
	int n;
	while (scanf("%d", &n) != EOF) {
		printf("%lld\n", dp145[n]);
	}
	return 0;
}
// 64 位输出请用 printf("%lld")