题解 | 最大 FST 距离

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n;
    cin>>n;
    vector<long long> arr(n,0); 
    for(int i=0;i<n;i++){
        cin>>arr[i];
    }
    long long max_U,min_U,min_V,max_V;
    for(long long i=0;i<n;i++){
        long long U,V;
        U=arr[i]*arr[i]+(i+1)*(i+1);
        V=arr[i]*arr[i]-(i+1)*(i+1);
        if(i==0){
            max_U=U;
            min_U=U;
        }else{
            if(max_U<U) max_U=U;
            if(min_U>U) min_U=U;
        }
        if(i==0){
            min_V=V;
            max_V=V;
        }else{
            if(min_V>V) min_V=V;
            if(max_V<V) max_V=V;
        }
    }
    cout<<max(max_U-min_U,max_V-min_V)<<endl;
    return 0;
}
// 64 位输出请用 printf("%lld")