给定一个表达式 expression
如 expression = "e + 8 - a + 5"
和一个求值映射,如 {"e": 1}
(给定的形式为 evalvars = ["e"]
和 evalints = [1]
),返回表示简化表达式的标记列表,例如 ["-1*a","14"]
"2x"
或 "-x"
这样的前导系数或一元运算符 。表达式按通常顺序进行求值:先是括号,然后求乘法,再计算加法和减法。例如,expression = "1 + 2 * 3"
的答案是 ["7"]
。
输出格式如下:
“b*a*c”
这样的项,只写 “a*b*c”
。"a*a*b*c"
的次数为 4。)。我们先写出答案的最大次数项,用字典顺序打破关系,此时忽略词的前导系数。["-2*a*a*a", "3*a*a*b", "3*b*b", "4*a", "5*c", "-6"]
。
示例:
输入:expression = "e + 8 - a + 5", evalvars = ["e"], evalints = [1] 输出:["-1*a","14"] 输入:expression = "e - 8 + temperature - pressure", evalvars = ["e", "temperature"], evalints = [1, 12] 输出:["-1*pressure","5"] 输入:expression = "(e + 8) * (e - 8)", evalvars = [], evalints = [] 输出:["1*e*e","-64"] 输入:expression = "7 - 7", evalvars = [], evalints = [] 输出:[] 输入:expression = "a * b * c + b * a * c * 4", evalvars = [], evalints = [] 输出:["5*a*b*c"] 输入:expression = "((a - b) * (b - c) + (c - a)) * ((a - b) + (b - c) * (c - a))", evalvars = [], evalints = [] 输出:["-1*a*a*b*b","2*a*a*b*c","-1*a*a*c*c","1*a*b*b*b","-1*a*b*b*c","-1*a*b*c*c","1*a*c*c*c","-1*b*b*b*c","2*b*b*c*c","-1*b*c*c*c","2*a*a*b","-2*a*a*c","-2*a*b*b","2*a*c*c","1*b*b*b","-1*b*b*c","1*b*c*c","-1*c*c*c","-1*a*a","1*a*b","1*a*c","-1*b*c"]
提示:
expression
的长度在 [1, 250]
范围内。evalvars, evalints
在范围 [0, 100]
内,且长度相同。