java入门--4110:圣诞老人的礼物-Santa Clau’s Gifts

学习了一下java的语法，就用poj上的题目做作练习，好更快的熟悉常用的java语法。

题目在这里 http://bailian.openjudge.cn/practice/4110/

import java.util.*;

public class Main {

private static class Ware {
public int value;
public int count;
public double v_p;
}

public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int rowcount = scan.nextInt();
int weight = scan.nextInt();
List<Ware>  wares= new ArrayList<Ware>();
for(int i = 0; i < rowcount; ++i) {
Ware w = new Ware();
w.value = scan.nextInt();
w.count = scan.nextInt();
w.v_p = w.value * 1.0 /w.count;
wares.add(w);
}

Collections.sort(wares, new Comparator<Ware>() {
@Override
public int compare(Ware o1, Ware o2) {
if (Math.abs(o1.v_p - o2.v_p) < 1e-6) {
return 0;
}
else if (o1.v_p > o2.v_p)
return -1;
else
return 1;
}
});

double sum = 0;
for (int i = 0; i < wares.size(); ++ i) {
Ware w = wares.get(i);
if (w.count <= weight) {
sum += w.value;
}
else {
sum += weight * w.v_p;
break;
}
weight -= w.count;
}
System.out.printf("%.1f", sum);
}
}

虽然简单，但是学习了java怎么处理输入；怎么排序；嵌套类默认会有一个外部类的引用，只能声明为static，才能在外部类的static函数中引用