题目链接

• f(1) = 1
• f(2) = 1 + 1 = 2
• f(3) = 1 + 2 + 1 = 4
• f(4) = 1 + 2 + 4 + 1 = 8

所以 f(n) = 2${}^{n-1}$

import java.util.Scanner;public class Solution {public int jumpFloorII(int target) {return 1 << (target - 1);}
}