Class Solution
Hard
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 applied the operators in the wrong order but had correct arithmetic , 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 applied the operators in this wrong order: ((7+3)*1)*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 applied the operators in this wrong order: ((3+5)*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 incorrectly done (6+0)*1, 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
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Constructor Summary
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Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Constructor Details
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Solution
public Solution()
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Method Details
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scoreOfStudents
public int scoreOfStudents(java.lang.String s, int[] answers)
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