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【LeetCode】70 - Climbing Stairs

时间:2015-07-27 00:03:55      阅读:172      评论:0      收藏:0      [点我收藏+]

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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? 

 
Solution:一个台阶的方法次数为1次,两个台阶的方法次数为2个。n个台阶的方法可以理解成上n-2个台阶,然后2步直接上最后一步;或者上n-1个台阶,再单独上一步
 
 1 int climbStairs(int n) {    //Runtime:0ms
 2     int a=1,b=2;
 3     if(n==1)return a;
 4     if(n==2)return b;
 5     int c=0;
 6     for(int i=3;i<=n;i++){
 7         c=a+b;
 8         a=b;
 9         b=c;
10     }
11     return c;
12 }
13 int climbStairs2(int n){    ////Runtime:0ms
14     if(n <= 2)return n;
15     int* step = new int[n];  
16     step[0] = 1;  
17     step[1] = 2;  
18     for(int i = 2; i < n; i++)step[i] = step[i-1] + step[i-2];  
19     return step[n-1];  
20 }

 

【LeetCode】70 - Climbing Stairs

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原文地址:http://www.cnblogs.com/irun/p/4678884.html

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