斐波那契数列

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import org.w3c.dom.Node;

import java.util.HashMap;

public class 斐波那契数列 {
    public static void main(String[] args) {
        fun(5);
        System.out.println(fun1(5));

    }

    /**
     * 非递归
     *
     * @param n
     * @return
     */
    public static void fun(int n) {
        long[] fn = new long[n + 1];
        fn[1] = 1;
        fn[2] = 2;
        for (int i = 3; i <= n; i++) {
            fn[i] = fn[i - 1] + fn[i - 2];
        }
        System.out.println(fn[n] + "");
    }

    /**
     * 递归
     *
     * @param n
     * @return
     */
    public static int fun1(int n) {
        if (n == 1) {
            return 1;
        }
        if (n == 2) {
            return 2;
        }
        return fun1(n - 1) + fun1(n - 2);
    }
}