1 #define _CRT_SECURE_NO_WARNINGS
2 #include <stdio.h>
3 #include <math.h>
4 #include <algorithm>
5 #include <stdlib.h>
6 #include <vector>
7 #include <map>
8 #include <queue>
9 #include <string>
10 #include <iostream>
11 #include <ctype.h>
12 #include <string.h>
13 #include <set>
14 #include <stack>
15 #include<functional>
16 using namespace std;
17 #define size 100001
18 #define maxn 1<<30
19 int past[size];//past[i]表示在第i天之后(包括i)买入,在第i天后面的某天卖出所能赚到的最大钱数
20 int pre[size];//pre[i]表示在第i天之前(包括i)卖出,在第i天之前买入所能获得的最大利润
21 int a[size];
22 /*
23
24
25 */
26 int main(){
27 int T;
28 cin >> T;
29 while (T--){
30 int n;
31 cin >> n;
32 memset(past, 0, sizeof(past));
33 memset(pre, 0, sizeof(pre));
34 for (int i = 1; i <= n; i++)
35 scanf("%d", &a[i]);
36 int low_prise = a[1];//买入的价格
37 pre[1] = 0;
38 for (int i = 2; i <= n; i++)
39 {
40 low_prise = min(low_prise, a[i]);
41 pre[i] = max(pre[i-1],a[i] - low_prise);//如果等于0 表示今天买入今天卖出
42 }
43 int high_prise = a[n];//卖出的价格
44 past[n] = 0;
45 for (int i = n - 1; i >= 1; i--)
46 {
47 high_prise = max(high_prise, a[i]);
48 past[i] = max(past[i+1],high_prise - a[i]);
49 }
50 int max_profit = 0;
51 for (int i = 1; i <= n; i++)
52 max_profit = max(max_profit, past[i] + pre[i]);
53 cout << max_profit << endl;
54 }
55 system("pause");
56 return 0;
57 }
