题解 | 货物堆放

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.*;
import java.util.*;

public class Main {
        static class Goods{
        long w;
        long v;
        long c;

        Goods(long w,long v,long c){
            this.w = w;
            this.v = v;
            this.c = c;
        }
    }


    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine().trim());

        Goods[] goods = new Goods[n];
        long total = 0;
        for(int i=0;i<n;i++){
            String[] str = br.readLine().trim().split("\\s+");
            long w = Long.parseLong(str[0]);
            long v = Long.parseLong(str[1]);
            long c = Long.parseLong(str[2]);

            goods[i]=new Goods(w, v,c);
            total += v;
        }

        Arrays.sort(goods,(x,y)->Long.compare(x.c*y.w, y.c*x.w));

        long sumCW = 0;
        long upperW = 0; 
        for (Goods g : goods) {
            
            sumCW += g.c*upperW;
            upperW += g.w;
        }

        long res = total -sumCW;

        out.println(res);
        out.flush();
        out.close();
        br.close();
    }
}