题目大意：给长度N的A1.....An 求(Ai-Aj)MAX

枚举n^2 其实动态维护最大值就好了

#include<iostream>

#include<cstdio>

using namespace std;

int t,a[],n,ans,MAX;

int main()

{

    scanf("%d",&t);

    while (t--)

    {

        scanf("%d",&n);

        for (int i=;i<=n;i++) scanf("%d",&a[i]);

        MAX=a[n];ans=-;

        for (int i=n-;i>=;i--)

        {

            ans=max(ans,a[i]-MAX);

            MAX=min(MAX,a[i]);

        }

        printf("%d\n",ans);

    }

}