366. 斐波纳契数列.cpp

class Solution {
public:
    /**
     * @param n: an integer
     * @return: an ineger f(n)
     */
    int fibonacci(int n) {
        // write your code here
        int a=0, b=1, c;
        if(n == 1)
            return 0;
        else if(n == 2)
            return 1;
        for(int i=3; i<=n; i++)
        {
            c = a + b;
            a = b;
            b = c;
        }
        return c;
    }
};