剑指 Offer 10- I. 斐波那契数列

java:

class Solution {
    public int fib(int n) {
        if (n == 0) return 0;//注！！
        if (n == 1) return 1;
        int tem1 = 0, tem2 = 1, sum = 0;
        while (n >= 2) {
            sum = (tem1 + tem2) % 1000000007;//注！！取模
            tem1 = tem2;
            tem2 = sum;
            n--;
        }
        return sum;
    }
}