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?

Note: Given n will be a positive integer.
其实就是一个斐波那契数列题，求斐波那契数列的第N项是多少。
class Solution {
public:
int climbStairs(int n) {
vector<int> ans(n, 0);
ans[0] = 1;
ans[1] = 2;
for (int i = 2; i < n; ++i) {
ans[i] = ans[i-1] + ans[i-2];
}
return ans[n-1];
}
};