題目分析：

前綴和啥的模擬一下就行了。

代碼：

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 
 4 const int maxn = 302000;
 5 
 6 int n,x,d[maxn],sta[maxn],top;
 7 long long minn[maxn],c[maxn],maxx[maxn];
 8 
 9 void read(){
10     scanf("%d%d",&n,&x);
11     for(int i=1;i<=n;i++) scanf("%d%lld",&d[i],&c[i]),c[i]=x-c[i];
 
12     for(int i=n;i>=1;i--) d[i] -= d[i-1];
13 }
14 
15 void work(){
16     long long ans = 0;
17     for(int i=1;i<=n;i++) ans = max(ans,c[i]);
18     for(int i=1;i<=n;i++) c[i] = c[i-1]+c[i];
19     maxx[0] = 3e18;
20     for(int i=2;i<=n;i++){
21     long long now = 2e18;
22     while(d[sta[top]] <= d[i]&&top>0
 
) {
23         now = min(minn[top],now);
24         top--;
25     }
26     sta[++top] = i; minn[top] = min(now,c[i-2]);
27     maxx[top] = min(1ll*d[i]*d[i]+minn[top],maxx[top-1]);
28     ans = max(ans,c[i]-maxx[top]);
29     }
30     printf("%lld\n",ans);
31 }
32 
33 int main(){
34     read();
35     work();
 
36     return 0;
37 }

codeforces1107G Vasya and Maximum Profit 【模擬】