通过初始化或者用户输入两个数组a和b，求两个数组的和差并输出，所谓和差就是去掉两个数组中相同的元素 然后将两个数组中的元素存放在一个新的数组中，且数组A中元素要在B数组元素之前(Through the initialization or user input two arrays a and B, for the two array and difference and output, and the difference is called to remove the same two ele