Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negative integers, +, -, *, / operators and empty spaces . The integer division should truncate toward zero. You may assume that the given ex
Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negativeintegers, +, -, *, / operators and empty spaces . The integer division should truncate toward zero. Example 1: Input: "3+2*2" Ou
一.命令式编程(imperative)和符号式编程(symblic) 命令式: import numpy as np a = np.ones(10) b = np.ones(10) * 2 c = b * a d = c + 1 当程序执行到 c=b∗a时,代码开始做对应的数值计算. 符号式编程于此不同,需要先给出一个函数的定义(可能十分复杂).当我们定义这个函数时,并不会做真正的数值计算.这类函数的定义中使用数值占位符.当给定真正的输入后,才会对这个函数进行编译计算. 符号式编程: 上面的例子