2017-2018 ACM-ICPC, NEERC, Southern Subregional Contest, qualification stage (Online Mirror, ACM-ICPC Rules, Teams Preferred) H. Load Testing

题意：给出一个数列，问修改差值最小，使得整个数列为严格递增，严格递减的数列，连续2个数字不能相同

思路：正的，反的跑一遍，记录当前这个如果为峰顶，左边要改多少，右边要改多少，

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=200005;
ll a[N];
ll l[N],r[N];
ll c[N];

int main(){
    int n;
    cin>>n;
    ll Max=0;
    int sss=0;
    for(int i=1;i<=n;i++){
        scanf("%lld",&a[i]);
        Max=max(Max,a[i]);
    }
    ll M=0;
    for(int i=1;i<=n;i++){
        if(a[i]<=M)
        {
            l[i]=l[i-1]+(M+1-a[i]);
            M++;
        }
        else {
            l[i]=l[i-1];
        }
        M=max(M,a[i]);
        c[i]=M;
      //  cout<<c[i]<<" ";
    }
    //cout<<endl;
     M=0;
    for(int i=n;i>=1;i--){
        if(a[i]<=M){
            r[i]=r[i+1]+M+1-a[i];
            M++;
        }
        else r[i]=r[i+1];
        M=max(M,a[i]);
        c[i]=max(c[i],M);
    }
    ll Min=1e18;
    Max++;
    for(int i=1;i<=n;i++){
        ll sum=c[i]-a[i];
        sum+=l[i-1]+r[i+1];
       // cout<<c[i]<<endl;
        Min=min(Min,sum);
    }
    cout<<Min<<endl;
}