题目链接：uva 11078 - Open Credit System
题目大意：给出n个数，找出两个数之间差的最大值，要求num[i] - num[j]（i < j)
解题思路：维护最大值Max，每次读取一个数时用Max - c，维护ans。
#include <stdio.h>
#include <algorithm>
using namespace std;
const int INF = 0x3f3f3f3f;
int main() {
int cas, n;
scanf("%d", &cas);
while (cas--) {
scanf("%d", &n);
int ans = -INF, Max = -INF, c;
for (int i = 0; i < n; i++) {
scanf("%d", &c);
ans = max(ans, Max - c);
Max = max(Max, c);
}
printf("%d\n", ans);
}
return 0;
}