题解归档 - cf2233A

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• 本地编号：cf2233A
• 本地来源：problems/cf2233A/idea.md
• 题目链接：https://codeforces.com/contest/2233/problem/A
• 原始标题：cf2233A - AI Project Development

思路

cf2233A - AI Project Development

pattern:
ceil division / compare two fixed strategies

claim:
Nikita has only two strategies, and each strategy has a deterministic
completion time measured in full hours.

formulas:

• No AI: both write from hour 0, speed is x+y, so time is
  ceil(n/(x+y)).
• AI: during the first z hours only Maxim writes. If x*z >= n, the project
  finishes during setup in ceil(n/x) hours. Otherwise, after setup there are
  n-x*z lines left and the speed is x+10*y, so time is
  z + ceil((n-x*z)/(x+10*y)).

answer:
Take the minimum of the two times.

check:
brute.cpp simulates full hours for both choices on small and random values.

代码

来源：problems/cf2233A/solution.cpp

#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll ceilDiv(ll a,ll b){
    return (a+b-1)/b;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin>>T;
    while(T--){
        ll n,x,y,z;
        cin>>n>>x>>y>>z;
        ll noAi=ceilDiv(n,x+y);
        ll withAi;
        if(x*z>=n) withAi=ceilDiv(n,x);
        else withAi=z+ceilDiv(n-x*z,x+10*y);
        cout<<min(noAi,withAi)<<"\n";
    }
    return 0;
}