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

int main()
{   
    int n;
    cin >> n;
    int a[n];
    for(int i = 0; i < n; i++) cin >> a[i];

    int std_diffrence = 0;
    for(int i = 0; i < n - 1; i++)
    {
        for(int j = 1; j < n; j++)
        {
            int real_diffrence = a[i] - a[j];
            if(fabs(real_diffrence) > fabs(std_diffrence)) std_diffrence = real_diffrence;
            else continue;
        }
    }

    cout << fabs(std_diffrence);
    return 0;
}

找最大，找最小，最后作差就好。

#include<stdio.h>
#include<string.h>
#include<stdlib.h> 
#include<math.h>
int cmp(const void*a,const void*b){
	return (*(int*)a-*(int*)b);
}

int main(){
	int n,i;scanf("%d",&n);
	int a[n];
	for(i=0;i<n;i++){
		scanf("%d",&a[i]);
		
	}
	qsort(a,n,sizeof(int),cmp);
	printf("%d",a[n-1]-a[0]);
    return 0;
}