斐波那契数列

保存中间计算的结果

class Solution {
public:
    int Fibonacci(int n) {
        if(n==0)return 0;
        if(n==1) return 1;
        int n0=0,n1=1,n2;
      while(--n)
          {
          n2=n0+n1;
          n0=n1;
          n1=n2;
      }
        return n2;
    }
};