xoj里比较经典且比较具有代表性的题目的代码-Comparison of classic and xoj in comparison with the subject of the representation of code! ! !

xoj上的一道题目，要求输入一连串的四则运算表达式，然后求值，输入的运算数字范围是0-9999，结果在32整形之内。此程序用到了堆栈，涉及知识比较广-xoj on a subject, asked to enter a series of arithmetic expressions, and then find the value, enter the operation number in the range 0-9999, the

Given a two-dimensional array of positive and negative integers, a sub-rectangle is any contiguous sub-array of size 1*1 or greater located within the whole array. The sum of a rectangle is the sum of all the elements in