题解 | 最大 FST 距离

import java.util.*;
import java.io.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int n = Integer.parseInt(st.nextToken());
        long maxT1=Integer.MIN_VALUE;
        long minT1=Integer.MAX_VALUE;
        long maxT2=Integer.MIN_VALUE;
        long minT2=Integer.MAX_VALUE;
        st = new StringTokenizer(br.readLine());
        int i=1;
        while(st.hasMoreTokens()){
            int v=Integer.parseInt(st.nextToken());
            long p = 1l*i*i;
            long d = (long)v*v;
            long T1= p + d;
            long T2= p - d;
            if(T1>maxT1){
                maxT1=T1;
            }
            if(T1<minT1){
                minT1=T1;
            }
            if(T2>maxT2){
                maxT2=T2;
            }
            if(T2<minT2){
                minT2=T2;
            }
            i++;
        }
        System.out.println(Math.max(maxT1-minT1,maxT2-minT2));
    }
}