Leetcode 70. Climbing stairs

You is climbing a stair case. It takes n steps to reach the top.

Each time you can either climb 1 or 2 steps. In what many distinct ways can you climb to the top?

It's obvious that this is a Fibonacci sequence, but we don't usually use recursion to solve

Class Solution {public:    int climbstairs (int n) {        if (n < 1) return 0;vector<int> VEC (n+1, 0); vec[0] = 1;ve C[1] = 1;for (int i = 2;i <= n;++i) {vec[i] = Vec[i-1] + vec[i-2];} return vec[n];}    ;

　　

Leetcode 70. Climbing stairs