158B - Taxi
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B. Taxi
time limit per test
3 seconds
memory limit per test
256 megabytes
input
standard input
output
standard outputAfter the lessons n groups of schoolchildren went outside and decided to visit Polycarpus to celebrate his birthday. We know that the i-th group consists of si friends (1?≤?si?≤?4),and they want to go to Polycarpus together. They decided to get there by taxi. Each car can carry at most four passengers. What minimum number of cars will the children need if all members of each group should ride in the same taxi (but one taxi can take more than one group)?
Input
The first line contains integer n (1?≤?n?≤?105) ― the number of groups of schoolchildren. The second line contains a sequence of integers s1,?s2,?...,?sn (1?≤?si?≤?4). The integers are separated by a space, si is the number of children in the i-th group.
Output
Print the single number ― the minimum number of taxis necessary to drive all children to Polycarpus.
Sample test(s)
input
5
1 2 4 3 3
output
4
input
8
2 3 4 4 2 1 3 1
output
5
Note
In the first test we can sort the children into four cars like this:
There are other ways to sort the groups into four cars.
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
int n1=0,n2=0,n3=0,count=0;
for(int i=0;i<n;i++)
{
int x=sc.nextInt();
if(x==1) n1++; if(x==2) n2++; if(x==3) n3++; if(x==4) count++;
}
if(n3>=n1) {count+=n3;count+=(n2+1)/2;}
else {
count+=n3+n2/2;n1-=n3;
if(n2%2==0&&n1>0) count+=(n1⑴)/4+1;
else count+=(n1+1)/4+1;
}
System.out.println(count);
}
} （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |