解题思路：

动态规划

class Solution {
    public int fib(int n) {
         if (n <= 1) return n;

        int[] dp = new int[n+1];
        dp[0] = 0;
        dp[1] = 1;

        for (int i = 2; i <= n; i++) {
            //取模运算防止整数溢出
            dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007;
        }
        return dp[n];
    }
}