Leetcode 70 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?
每次爬一到两步，到终点有多少种办法？
简单DP，往后1步2步转移。

class Solution {
public:
int climbStairs(int n) {
vector<int> dp(n+1,0);
dp[0]=1;
for(int i=0;i<=n;i++)
{
if(i+1<=n) dp[i+1]+=dp[i];
if(i+2<=n) dp[i+2]+=dp[i];
}
return dp
;
}
};