CF730L.Expression Queries
NOI/NOI+/CTSC
通过率:0%
时间限制:4.00s
内存限制:512MB
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题目描述
A simplified arithmetic expression (SAE) is an arithmetic expression defined by the following grammar:
::= | + | * | ( ) ::= | ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
In other words it's a correct arithmetic expression that is allowed to contain brackets, numbers (possibly with leading zeros), multiplications and additions. For example expressions "(0+01)", "0" and "1*(0)" are simplified arithmetic expressions, but expressions "2-1", "+1" and "1+2)" are not.
Given a string _s_1_s_2...s|s| that represents a SAE; s__i denotes the i-th character of the string which can be either a digit ('0'-'9'), a plus sign ('+'), a multiplication sign ('*'), an opening round bracket '(' or a closing round bracket ')'.
A part s__l__s__l + 1...s__r of this string is called a sub-expression if and only if it is a SAE.
You task is to answer m queries, each of which is a pair of integers l__i, r__i (1 ≤ l__i ≤ r__i ≤ |s|). For each query determine whether the corresponding part of the given string is a sub-expression and in case it's a sub-expression calculate its value modulo 1000000007 (109 + 7). The values should be calculated using standard operator priorities.
简化算术表达式(SAE)是一种由如下文法定义的算术表达式:
<SAE> ::= <Number> | <SAE>+<SAE> | <SAE>*<SAE> | (<SAE>)<Number> ::= <Digit> | <Digit><Number><Digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
换言之,它是一个合法的算术表达式,允许包含括号、数字(数字可能含有前导零)、乘法和加法运算。例如,表达式 "(0+01)"、"0" 和 "1*(0)" 均为简化算术表达式;但表达式 "2-1"、"+1" 和 "1+2)" 则不是。
给定一个字符串 s1s2…s∣s∣,它表示一个 SAE;其中 si 表示该字符串的第 i 个字符,可以是数字('0'–'9')、加号('+')、乘号('*')、左圆括号 '(' 或右圆括号 ')'。
该字符串的一个子串 slsl+1…sr 被称为子表达式,当且仅当它本身是一个 SAE。
你的任务是回答 m 个查询,每个查询由一对整数 li,ri 组成(满足 1≤li≤ri≤∣s∣)。对每个查询,请判断该字符串对应区间是否构成一个子表达式;若是子表达式,则计算其值对 1000000007(即 109+7)取模的结果。计算时需遵循标准的运算符优先级规则。
输入格式
The first line of the input contains non-empty string s (1 ≤ |s| ≤ 4·105) which represents a correct SAE. Each character of the string can be one of the following characters: '*', '+', '(', ')' or a digit ('0'-'9'). The expression might contain extra-huge numbers.
The second line contains an integer m (1 ≤ m ≤ 4·105) which is the number of queries. Each of the next m lines contains two space-separated integers l__i, r__i (1 ≤ l__i ≤ r__i ≤ |s|) — the i-th query.
输入的第一行包含一个非空字符串 s(1 ≤ ∣s∣ ≤ 4⋅105),表示一个合法的 SAE(简单算术表达式)。字符串中的每个字符可以是以下字符之一:\*、+、(、) 或一个数字('0'–'9')。该表达式可能包含极大数值。
第二行包含一个整数 m(1 ≤ m ≤ 4⋅105),表示查询次数。接下来的 m 行中,每行包含两个以空格分隔的整数 li、ri(1 ≤ li ≤ ri ≤ ∣s∣),表示第 i 个查询。
输出格式
The i-th number of output should be the answer for the i-th query. If the i-th query corresponds to a valid sub-expression output the value of the sub-expression modulo 1000000007 (109 + 7). Otherwise output -1 as an answer for the query. Print numbers on separate lines.
第 i 个输出数字应为第 i 个查询的答案。若第 i 个查询对应一个有效的子表达式,则输出该子表达式的值对 1000000007(即 109+7)取模的结果;否则,输出 −1 作为该查询的答案。每个数字单独占一行。
输入输出样例
输入#1
((1+2)*3+101*2) 6 8 14 1 6 2 10 11 14 5 5 4 5
输出#1
205 -1 10 2 2 -1
输入#2
(01) 1 1 4
输出#2
1
输入解题思路,AI测评打分。不知道怎么写?