MCIPC Contest 2 P5 - Holiday Chocolates
View as PDFThis winter at Martingrove, you have decided to help out a fundraiser that is selling chocolates. In the fundraiser,  students, numbered from 
 to 
, have ordered chocolates, where the 
 student has ordered 
 chocolates for themselves. Additionally, when a student orders chocolates for themselves, they can also choose to order chocolates for some friends. Because of this, the fundraiser got 
 additional orders of chocolates, where in every additional order 
, student 
 buys student 
 some chocolates.
However, as a part of a grand marketing scheme, if student  wants to buy student 
 chocolates, student 
 must order student 
 the same amount of chocolates that student 
 received, including the ones that student 
 bought for themselves. Note that a student cannot give themselves another order of chocolates, or give another student multiple orders of chocolates.
Because you have been tasked with delivering the chocolates, and you do not like hard work, you wish for there to be as few sales of chocolate as possible. You can coerce  people to not buy themselves chocolates, i.e., you can set 
 of the 
 to 
. However, they will still buy chocolates for their friends. What is the minimum amount of chocolates you will have to deliver?
Constraints
The pair  is unique.
Before setting  of the 
 to 
, the total number of chocolates needed to be delivered will be less than 
.
There does not exist a cycle of students  such that student 
 sent chocolates to student 
, student 
 sent chocolates to student 
, 
, student 
 sent chocolates to student 
.
Subtask 1 [20%]
Each student can send chocolates to at most  other student and can also receive chocolates from at most 
 other student.
Subtask 2 [30%]
Subtask 3 [50%]
No additional constraints.
Input Specification
The first line contains the integers , 
, and 
, separated by a space.
The second line contains  space separated integers, where the 
 integer represents the number of chocolates 
 the 
 person will buy for themselves.
The  line of the next 
 lines will contain the integers 
 and 
 separated by a space, where student 
 will give chocolates to student 
.
Output Specification
Output a single integer, the minimum number of chocolates which you will have to deliver after coercing  students into not buying chocolates for themselves.
Sample Input 1
4 4 1
1 5 1 1
1 2
2 3
3 4
2 4
Sample Output 1
8
Explanation for Sample 1
Student  buys themselves 
 chocolate, receiving 
 chocolate in total.
Student  buys themselves 
 chocolates and receives 
 chocolate from student 
, receiving 
 chocolates in total.
Student  buys themselves 
 chocolate, and receives 
 chocolates from student 
, receiving 
 chocolates in total.
Student  buys themselves 
 chocolate, receives 
 chocolates from student 
 and also receives 
 chocolates from student 
, receiving 
 chocolates in total.
Before preventing  of the students from buying themselves chocolates, the total amount of chocolates needed to be delivered is 
.
The optimal solution is to make student  not buy themselves chocolates, which results in 
 chocolates needing to be delivered.
Sample Input 2
6 8 3
3 4 2 5 10 1
1 3
1 2
1 4
2 4
4 5
3 5
5 6
2 5
Sample Output 2
22
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