HDU 5805 NanoApe Loves Sequence

处理出每个位置左边的最大值和右边的最大值。然后就可以o(1)计算去掉某位置的最大值了。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-8;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
inline int read()
{
    char c = getchar();  while(!isdigit(c)) c = getchar();
    int x = 0;
    while(isdigit(c)) { x = x * 10 + c - ‘0‘; c = getchar(); }
    return x;
}

const int maxn=100000+10;
int T,n,a[maxn],L[maxn],R[maxn];
LL ans;

int main()
{
    scanf("%d",&T);
    while(T--)
    {
        ans=0; memset(L,0,sizeof L); memset(R,0,sizeof R);
        scanf("%d",&n); for(int i=1;i<=n;i++) scanf("%d",&a[i]);
        for(int i=2;i<=n;i++) L[i]=max(L[i-1],abs(a[i]-a[i-1]));
        for(int i=n-1;i>=1;i--) R[i]=max(R[i+1],abs(a[i]-a[i+1]));
        for(int i=1;i<=n;i++)
        {
            if(i==1) ans=ans+R[2];
            else if(i==n) ans=ans+L[n-1];
            else ans=ans+max(L[i-1],max(R[i+1],abs(a[i-1]-a[i+1])));
        }
        printf("%lld\n",ans);
    }
    return 0;
}