https://ac.nowcoder.com/acm/contest/322/F

题解：前缀最大值，后缀最大值？？？

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=200000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q,ans;
int a[N];
int b[N];
int c[N];
char str;
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        b[i]=max(a[i],b[i-1]);
    }
    int ans=0;
    for(int i=n;i>=1;i--){
        c[i]=max(a[i],c[i+1]);
        if(i!=n)
        ans=max(ans,abs(b[i]-c[i+1]));
    }
    cout << ans << endl;
    //cout << "Hello world!" << endl;
    return 0;
}