首页 > 代码库 > Climbing Stairs
Climbing Stairs
Climbing Stairs
You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
1 import java.math.BigInteger; 2 3 public class Solution { 4 public int climbStairs(int n) { 5 int num2s = n / 2; 6 int ways = 0; 7 int num1s = n - num2s * 2; 8 for(int i = num2s; i >= 0; i--){ 9 ways += selectMFromN(num2s + num1s, num2s);10 num2s--;11 num1s += 2;12 }13 return ways;14 }15 /**16 * 计算C(N,M) = n * (n - 1) *...(n - m + 1) / m!17 * @param n18 * @param m19 * @return20 */21 public int selectMFromN(int n, int m){22 BigInteger fenzi = new BigInteger("1");23 BigInteger fenmu = new BigInteger("1");24 for(int i = n ; i >= n - m + 1;i--){25 fenzi = fenzi.multiply(new BigInteger(String.valueOf(i)));26 }27 for(int i = m ; i >= 1;i--){28 fenmu = fenmu.multiply(new BigInteger(String.valueOf(i)));29 }30 return (fenzi.divide(fenmu)).intValue();31 }32 }
这里要求C(N,M)有溢出，我用BigInteger处理的
Climbing Stairs
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。