<JZOJ1329>旅行

贪心大水题

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#define rint register int
using std::max;
using std::min;
template <class T>inline void read(T &X)
{
    X=;int W=;char ch=;
    while(!isdigit(ch))W|=ch=='-',ch=getchar();
    while(isdigit(ch))X=(X<<)+(X<<)+(ch^),ch=getchar();
    X=W?-X:X;return;
}
int n;
long long a[];
long long ans=;
int main()
{
    read(n);
    for(rint i=;i<=n;++i) read(a[i]);
    for(rint i=;i<=n;++i)
    {
        int lst=a[i];
        if(a[i]>a[i+] && a[i]>a[i-])
            a[i]=max(a[i-],a[i+]),ans+=lst-a[i];
        if(a[i]<a[i+] && a[i]<a[i-])
            a[i]=min(a[i-],a[i+]),ans+=a[i]-lst;
    }
    for(rint i=;i<=n;++i)
        ans+=abs(a[i]-a[i-]);
    printf("%lld\n",ans);
return ;
}