贪心

//注意：最多只能一笔交易
import java.util.*;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[]v = sc.nextLine().split(" ");
        int[] p = new int[v.length];
        for(int i=0;i<v.length;++i) {
            p[i] = Integer.parseInt(v[i]);
        }
        int max_profit = 0;
        int min_index=0;
        for(int i=0;i<v.length;++i) {
            if(p[i]-p[min_index]>0) {
                max_profit = max(max_profit,p[i]-p[min_index]);
            }else{
                min_index=i;
            }
        }
        System.out.println(max_profit);


    }

    public static int max(int... a) {
        return Arrays.stream(a).max().getAsInt();
    }



}

暴力

//注意：最多只能一笔交易
import java.util.*;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[]v = sc.nextLine().split(" ");
        int[] p = new int[v.length];
        for(int i=0;i<v.length;++i) {
            p[i] = Integer.parseInt(v[i]);
        }
        int max=0;
        for(int i=p.length-1;i>0;--i) {
            for(int j=i-1;j>=0;--j) {
                max = max(p[i]-p[j],max);
            }
        }
         System.out.println(max);
    }

    public static int max(int... a) {
        return Arrays.stream(a).max().getAsInt();
    }



}