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?
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c++ code:
class Solution {
public:
int climbStairs(int n) {
if(1==n) return 1;
if(2==n) return 2;
int a=1,b=2;
for(int i=3;i<=n;i++) {
b = a + b;
a = b - a;
}
return b;
}
};原文：http://blog.csdn.net/itismelzp/article/details/51524345