Fib数列

题目链接：力扣Fib数列

递归（超时）

class Solution {
    public int fib(int n) {
        if(n==0)
        return 0;
if(n==1||n==2)
return 1;
else
return fib(n-1)+fib(n-2);
    }
}

递推

class Solution {
    public int fib(int n) {
        long f[] = new long[105];
        f[1] = 1;
        f[2] = 1;
        for(int i = 3;i<=n;i++)
        {
            f[i] = (f[i-1]%(1000000007))+(f[i-2]%(1000000007));
        }
        return (int)(f[n]%(1000000007));
    }
}