简单的递归

int result = 0;

    /**
     * 递归求n+(n-1)+(n-2)+...+1的和
     * @param n
     * @return
     */
    public int recursion(int n) {
        if( n > 0 ) {
            result = result + n;
            recursion(n - 1);
        }
        return result;
    }