506C Mr. Kitayuta vs. Bamboos

分析

代码

#include<bits/stdc++.h>
using namespace std;
#define int long long
int n,m,p,k,a[],h[],now[],cnt[];
inline bool ck(int mid){
    int i,j,tot=,res=;
    for(i=;i<=n;i++)now[i]=h[i]+a[i]*m,tot+=max(0ll,(now[i]-mid-+p)/p);
    for(i=;i<=m;i++)cnt[i]=;
    if(tot>m*k)return ;
    for(i=;i<=n;i++)if(now[i]>mid)
      for(j=(now[i]-mid-)%p+;j<=now[i]-mid;j+=p)
        if(j<=h[i])cnt[]++;else if(j>h[i]+(m-)*a[i])return ;else cnt[(j-h[i]-+a[i])/a[i]]++;
    for(i=;i<m;i++){
      res+=cnt[i];
      res=max(0ll,res-k);
    }
    return !res;
}
signed main(){
    int i,j;scanf("%lld%lld%lld%lld",&n,&m,&k,&p);
    for(i=;i<=n;i++)scanf("%lld%lld",&h[i],&a[i]);
    int le=,ri=1e15;
    while(ri-le>){
      int mid=(le+ri)>>;
      if(ck(mid))ri=mid;
        else le=mid;
    }
    printf("%lld\n",ri);return ;
}