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 = 302000;

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=1;i<=n;i++) scanf("%d%lld",&d[i],&c[i]),c[i]=x-c[i];
    for(int i=n;i>=1;i--) d[i] -= d[i-1];
}

void work(){
    long long ans = 0;
    for(int i=1;i<=n;i++) ans = max(ans,c[i]);
    for(int i=1;i<=n;i++) c[i] = c[i-1]+c[i];
    maxx[0] = 3e18;
    for(int i=2;i<=n;i++){
    long long now = 2e18;
    while(d[sta[top]] <= d[i]&&top>0) {
        now = min(minn[top],now);
        top--;
    }
    sta[++top] = i; minn[top] = min(now,c[i-2]);
    maxx[top] = min(1ll*d[i]*d[i]+minn[top],maxx[top-1]);
    ans = max(ans,c[i]-maxx[top]);
    }
    printf("%lld
",ans);
}

int main(){
    read();
    work();
    return 0;
}