最简单的动态规划了

class Solution {
public:
    int Fibonacci(int n) {
        if(n == 0 || n == 1) return n;
        int a = 0, b = 1, c;
        for(int i = 0; i <= n - 2; i++)
        {
            c = a + b;
            a = b;
            b = c;
        }
        return c;
    }
};