[cf505E]Mr. Kitayuta vs. Bamboos

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define N 100005
 4 #define ll long long
 5 priority_queue<pair<ll,int> >q;
 6 int n,m,k,p,h[N],a[N];
 7 ll f[N];
 8 ll calc(int k){
 9     if (f[k]/a[k]<m)return f[k]/a[k];
10     if (f[k]-1LL*m*a[k]<h[k])return m;
11     return m+1;
12 }
13 bool pd(ll s){
14     for(int i=1;i<=n;i++)f[i]=s;
15     while (!q.empty())q.pop();
16     for(int i=1;i<=n;i++)q.push(make_pair(-calc(i),i));
17     for(int i=1;i<=m;i++){
18         for(int j=1;j<=k;j++){
19             int x=q.top().second;
20             q.pop();
21             f[x]+=p;
22             q.push(make_pair(-calc(x),x));
23         }
24         if (-q.top().first<=i)return 0;
25     }
26     return (-q.top().first>m);
27 }
28 int main(){
29     scanf("%d%d%d%d",&n,&m,&k,&p);
30     for(int i=1;i<=n;i++)scanf("%d%d",&h[i],&a[i]);
31     ll l=0,r=1e13;
32     for(int i=1;i<=n;i++)l=max(l,1LL*a[i]);
33     while (l<r){
34         ll mid=(l+r>>1);
35         if (pd(mid))r=mid;
36         else l=mid+1;
37     }
38     printf("%lld",l);
39 }