UVA - 11078 Open Credit System

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int A[100000],n;

int main(){
    int t;
    scanf("%d",&t);
    while (t--){
        scanf("%d",&n);
        for (int i = 0; i < n; i++)
            scanf("%d",&A[i]);
        int ans = A[0] - A[1];
        int MaxAi = A[0];
        for (int j = 1; j < n; j++){
            ans = max(ans,MaxAi-A[j]);
            MaxAi = max(MaxAi,A[j]);
        }
        printf("%d\n",ans);
    }
    return 0;
}