2019. The Score of Students Solving Math Expression
https://leetcode.com/problems/the-score-of-students-solving-math-expression
Description
You are given a string s
that contains digits 0-9
, addition symbols '+'
, and multiplication symbols '*'
only, representing a valid math expression of single digit numbers (e.g., 3+5*2
). This expression was given to n
elementary school students. The students were instructed to get the answer of the expression by following this order of operations:
Compute multiplication, reading from left to right; Then,
Compute addition, reading from left to right.
You are given an integer array answers
of length n
, which are the submitted answers of the students in no particular order. You are asked to grade the answers
, by following these rules:
If an answer equals the correct answer of the expression, this student will be rewarded
5
points;Otherwise, if the answer could be interpreted as if the student used the incorrect order of operations, once or multiple times, this student will be rewarded
2
points;Otherwise, this student will be rewarded
0
points.
Return the sum of the points of the students.
Example 1:

**Input:** s = "7+3*1*2", answers = [20,13,42]
**Output:** 7
**Explanation:** As illustrated above, the correct answer of the expression is 13, therefore one student is rewarded 5 points: [20,**13**,42]
A student might have used this incorrect order of operations: 7+3=10, 10*1=10, 10*2=20. Therefore one student is rewarded 2 points: [**20**,13,42]
The points for the students are: [2,5,0]. The sum of the points is 2+5+0=7.
Example 2:
**Input:** s = "3+5*2", answers = [13,0,10,13,13,16,16]
**Output:** 19
**Explanation:** The correct answer of the expression is 13, therefore three students are rewarded 5 points each: [**13**,0,10,**13**,**13**,16,16]
A student might have used this incorrect order of operations: 3+5=8, 8*2=16. Therefore two students are rewarded 2 points: [13,0,10,13,13,**16**,**16**]
The points for the students are: [5,0,0,5,5,2,2]. The sum of the points is 5+0+0+5+5+2+2=19.
Example 3:
**Input:** s = "6+0*1", answers = [12,9,6,4,8,6]
**Output:** 10
**Explanation:** The correct answer of the expression is 6.
If a student had used some incorrect order of operations, the answer would also be 6.
By the rules of grading, the students will still be rewarded 5 points (as they got the correct answer), not 2 points.
The points for the students are: [0,0,5,0,0,5]. The sum of the points is 10.
Constraints:
3 <= s.length <= 31
s
represents a valid expression that contains only digits0-9
,'+'
, and'*'
only.All the integer operands in the expression are in the inclusive range
[0, 9]
.1 <=
The count of all operators ('+'
and'*'
) in the math expression<= 15
Test data are generated such that the correct answer of the expression is in the range of
[0, 1000]
.n == answers.length
1 <= n <= 104
0 <= answers[i] <= 1000
ac
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