import java.util.*;
public class Solution {
// 斐波那契思想。只是注意一下 “先后次序不同算不同的结果” ，需要修正一下前三步
// 最优方法：迭代
public int jumpFloor(int jumpFloor) {
if (jumpFloor <= 2) {
return jumpFloor;
}
else {
int pre = 2;
int pre_pre = 1;
int sum = 0;
for (int i = 3; i <= jumpFloor; i++) {
sum = pre + pre_pre;
pre_pre = pre;
pre = sum;
}
return sum;
}
}
public static void main(String[] args) {
Solution s = new Solution();
int n = 7;
int ans = s.jumpFloor(n);
System.out.println(ans);
}
}
