Java实现 洛谷 P1909 买铅笔
         
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import java.util.Arrays;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		
		int qianbisum = in.nextInt();
		int[] a = new int[3];
		int[] b = new int[3];
		
		int sum=0;
		int[] count = new int[3];
		
		for(int i=0;i<3;i++){
			a[i]=in.nextInt();
			b[i]=in.nextInt();
			
			if(qianbisum%a[i] != 0){
				sum = (qianbisum/a[i]+1) * b[i];
			}else{
				sum = qianbisum/a[i] * b[i];
			}
			
			count[i] = sum;			
		}
		Arrays.sort(count);
		System.out.println(count[0]);
	}
}