题目链接

剑指 Offer 10- I. 斐波那契数列

思路

递推，思路可以参考剑指 Offer 10- II. 青蛙跳台阶问题

代码

class Solution {
    public int fib(int n) {
        int a = 0;
        int b = 1;
        int sum;
        
        for(int i = 0; i < n; i++){
            sum = (a + b) % 1000000007;
            a = b;
            b = sum;
        }

        return a;
    }
}