1.输入一无符号整数num，要求通过计算，得到它的二进制方式，并输出在显示屏上 2.求3X3矩阵对角线元素之和 3.求n*n矩阵对角线元素之和 4.鞍点 5.字符串按逆序重新存放 6.两个字符串S1和S2比较-1. Enter an unsigned integer num, requested by calculation, to get it in binary mode, and output on the display 2. 3X3 matrix diagonal elements of the request and 3. seek n* n diagonal elements of the matrix and 4 saddle point 5. string in reverse order to re-store the two strings S1 and S2 6. comparison