建立一元多项式并按照指数降序排列输出多项式，将一元多项式输入并存储在内存中，能够完成两个多项式的加减运算并输出结果-The establishment of a polynomial and the index in descending order according to the output polynomial, will be a polynomial input and stored in memory to complete the addition and subtraction of two polynomials, and the output