[題解]基地台

a141. 基地台

#include <bits/stdc++.h>
#define ll long long
#define Orz ios::sync_with_stdio(0),cin.tie(0)
#define N 50005
using namespace std;
int n,k,arr[N];

//確認直徑可否覆蓋全部（greedy）
bool check(int sum){
    int max_cover = arr[0]+sum;
    int cnt=1;
    for(int i=1;i<n;i++){
        if(max_cover < arr[i]){
            max_cover = arr[i]+sum;
            cnt++;
        }
    }
    return (cnt<=k);
}

void solve(){
    cin>>n>>k;
    for(int i=0;i<n;i++)cin>>arr[i];
    sort(arr,arr+n);
    int l = 1,r = ceil((arr[n-1]-arr[0])/k);
    //區間[l,r]二分搜尋直徑
    while(l<r){
        int mid = (l+r)/2;
        if(check(mid))r = mid;
        else l = mid+1;
    }
    cout<<l<<endl;
}

signed main(){
    Orz;
    int t;t = 1;
    while(t--){
        solve();
    }
}