70. Climbing Stairs

Difficulty: Easy

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?

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

DP: dp[i]=dp[i-1]+dp[i-2]