Codeforces 847H - Load Testing

847H - Load Testing

思路：dp。

代码：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mem(a,b) memset(a,b,sizeof(a)

const int N=1e5+;
ll dp[N]={};
ll dp1[N]={};
ll a[N];
ll t[N]={};
ll t1[N]={};
int main()
{
    ios::sync_with_stdio(false);
    cin.tie();
    int n;
    cin>>n;
    for(int i=;i<=n;i++)cin>>a[i];

    t[]=a[];
    for(int i=;i<=n;i++)
    {
        if(a[i]<=t[i-])
        {
            dp[i]=dp[i-]+t[i-]-a[i]+;
            t[i]=t[i-]+;
        }
        else
        {
            t[i]=a[i];
            dp[i]=dp[i-];
        }
    }

    t1[n]=a[n];
    for(int i=n-;i>=;i--)
    {
        if(a[i]<=t1[i+])
        {
            dp1[i]=dp1[i+]+t1[i+]-a[i]+;
            t1[i]=t1[i+]+;
        }
        else
        {
            t1[i]=a[i];
            dp1[i]=dp1[i+];
        }
    }

    ll ans=min(dp1[],dp[n]);
    for(int i=;i<=n-;i++)
    ans=min(ans,dp1[i]+dp[i]-min(t[i],t1[i])+a[i]); 

    cout<<ans<<endl;
    return ;
}