HDOJ 1009

这道题比较简单，但是一直MLE.

import java.util.Arrays;

import java.util.Scanner;

public class Main {

    public static void main(String[] args)

    {

        Scanner scanner=new Scanner(System.in);

        short M=0,N=0,j,f;

        Food[] fs;

        while(true)

        {

            M=scanner.nextShort();

            N=scanner.nextShort();

            if(N==-1 && M==-1)

                break;

            fs=new Food[N];

            for(short i=0;i<N;i++)

            {

                fs[i]=new Food(scanner.nextShort(),scanner.nextShort());

            }

            Arrays.sort(fs);//注意这里的N和String的subString的endIndex一样都不包含在内

            float sum=0;

            short i=0;

            while(M>0 && i<N)

            {

                if(fs[i].f>=M)

                {

                    sum+=M*fs[i].j*1.0f/fs[i].f;

                    M=(short)(M-M);

                }

                else {

                    sum+=fs[i].j;

                    M=(short)(M-fs[i].f);

                }

                i++;

            }

            System.out.println(String.format("%.3f", sum));

        }

    }

    static class Food implements Comparable<Food>

    {

        public short j;

        public short f;

        

        public Food(short j,short f)

        {

            this.j=j;

            this.f=f;

        }

        @Override

        public int compareTo(Food o) {

            // TODO Auto-generated method stub

            if(this.j*1.0f/this.f>=o.j*1.0f/o.f)

                return -1;

            else

                return 1;

        }

    }

}