codeforces1107G Vasya and Maximum Profit 【模拟】

题目分析：

前缀和啥的模拟一下就行了。

代码：

 #include<bits/stdc++.h>
 using namespace std;

 const int maxn = ;

 int n,x,d[maxn],sta[maxn],top;
 long long minn[maxn],c[maxn],maxx[maxn];

 void read(){
     scanf("%d%d",&n,&x);
     for(int i=;i<=n;i++) scanf("%d%lld",&d[i],&c[i]),c[i]=x-c[i];
     for(int i=n;i>=;i--) d[i] -= d[i-];
 }

 void work(){
     long long ans = ;
     for(int i=;i<=n;i++) ans = max(ans,c[i]);
     for(int i=;i<=n;i++) c[i] = c[i-]+c[i];
     maxx[] = 3e18;
     for(int i=;i<=n;i++){
     long long now = 2e18;
     while(d[sta[top]] <= d[i]&&top>) {
         now = min(minn[top],now);
         top--;
     }
     sta[++top] = i; minn[top] = min(now,c[i-]);
     maxx[top] = min(1ll*d[i]*d[i]+minn[top],maxx[top-]);
     ans = max(ans,c[i]-maxx[top]);
     }
     printf("%lld\n",ans);
 }

 int main(){
     read();
     work();
     return ;
 }