Maximum Profit
You can obtain profits from foreign exchange margin transactions.
你可以从外汇保证金交易中获得利润。
For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.
例如，如果你以每美元100日元的汇率购买1000美元，然后以每美元108日元的汇率出售，你可以得到（108-100）×1000=8000日元。
Write a program which reads values of a currency Rt at a certain time t (t=0,1,2,…n−1), and reports the maximum value of Rj−Ri where j>i .
编写一个程序，在特定时间t（t=0,1,2，…n−1）读取货币rt的值，并报告rj−ri的最大值，其中j>i。
Input
The first line contains an integer n. In the following n lines, Rt (t=0,1,2,…n−1) are given in order.
第一行包含一个整数n。在下面的n行中，rt（t=0,1,2，…n−1）按顺序给出。
Output
Print the maximum value in a line.
打印一行中的最大值。
Constraints
2≤n≤200,000
1≤Rt≤109
Sample Input 1
6
5
3
1
3
4
3
Sample Output 1
3
Sample Input 2
3
4
3
2
Sample Output 2
-1
code
/*
^....0
^ .1 ^1^
.. 01
1.^ 1.0
^ 1 ^ ^0.1
1 ^ ^..^
0. ^ 0^
.0 1 .^
.1 ^0 .........001^
.1 1. .111100....01^
00 ^ 11^ ^1. .1^
1.^ ^0 0^
.^ ^0..1
.1 1..^
1 .0 ^ ^
^ 00. ^^0.^
1 ^ 0 ^^110.^
0. 0 ^ ^^^10.01
^^ 010^ 1 1 ^^^1110.1
0001 10 0 ^ 1.1 ^^^1111110
0^ 10 . 01 ^^ ^^ ^^^1111^1.^ ^^^
10 10^ 0^ ^^111^^^0.1^ 1....^
11 0 ^^11^^^ 0.. ....1^ ^ ^
1. 0^ ^11^^^ ^ 1 111^ ^ 0.
10 00 11 ^^^^^ 1 0 1.
0^ ^0 ^0 ^^^^ 0 0.
0^ 1.0 .^ ^^^^ 1 1 .0
^.^ ^^ 0^ ^1 ^^^^ 0. ^.1
1 ^ 11 1. ^^^ ^ ^ ..^
^..^ ^1 ^.^ ^^^ .0 ^.0
0..^ ^0 01 ^^^ .. 0..^
1 .. .1 ^.^ ^^^ 1 ^ ^0001
^ 1. 00 0. ^^^ ^.0 ^.1
. 0^. ^.^ ^.^ ^^^ ..0.0
1 .^^. .^ 1001 ^^ ^^^ . 1^
. ^ ^. 11 0. 1 ^ ^^ 0.
0 ^. 0 ^0 1 ^^^ 0.
0.^ 1. 0^ 0 .1 ^^^ ..
.1 1. 00 . .1 ^^^ ..
1 1. ^. 0 .^ ^^ ..
0. 1. .^ . 0 .
.1 1. 01 . . ^ 0
^.^ 00 ^0 1. ^ 1 1
.0 00 . ^^^^^^ .
.^ 00 01 ..
1. 00 10 1 ^
^.1 00 ^. ^^^ .1
.. 00 .1 1..01 ..
1.1 00 1. ..^ 10
^ 1^ 00 ^.1 0 1 1
.1 00 00 ^ 1 ^
. 00 ^.^ 10^ ^^
1.1 00 00 10^
..^ 1. ^. 1.
0 1 ^. 00 00 .^
^ ^. ^ 1 00 ^0000^ 0 01
1 0 ^. 00.0^ ^1.0.1 1.00.1 11
. 1 0 1^^0.01 ^^^ 01
.^ ^ 1 1^^ ^.^
1 1 0.
.. 1 ^
1 1
^ ^ .0
1 ^ 1
.. 1.1 ^0.0
^ 0 1..01^^100000..0^
1 1 ^ 1 ^^1111^ ^^
0 ^ ^ 1 1000^
.1 ^.^ . 00
.. 1.1 0. 0
1. . 1. .^
1. 1 1. ^0
^ . ^.1 00 01
^.0 001. .^
*/
// Virtual_Judge —— Maximum Profit Aizu - ALDS1_1_D.cpp created by VB_KoKing on 2019,04,24,19.
/* Procedural objectives：
Procedural thinking：
在下标自增的过程中，将现阶段rt最小值保存下来。
Functions required by the program:
Variables required by the program:
*/
/* My dear Max said：
"I like you,
So the first bunch of sunshine I saw in the morning is you,
The first hurricane that passed through your ear is you,
The first star you see is also you.
The world I see is all your shadow."
FIGHTING FOR OUR FUTURE！！！
*/
#include <set>
#include <map>
#include <list>
#include <deque>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <string>
#include <vector>
#include <cctype>
#include <sstream>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
int main()
{
int n;
cin>>n;
int rt[200000];
memset(rt,0, sizeof(rt));
for (int i = 0; i < n; ++i) {
cin >> rt[i];
}
int maxv=-2000000000,minv=rt[0];
for (int i = 1; i < n; i++) {
maxv=max(maxv,rt[i]-minv); //更新最大值
minv=min(minv,rt[i]); //暂存现阶段的最小值
}
cout<<maxv<<endl;
return 0;
}