P1824 attacking cows, P1824 attacking cows

P1824 attacking cows, P1824 attacking cows
Description

Farmer John built a cowshed with N (2 <= N <= 100,000) compartments distributed in a straight line in the coordinates of x1 ,..., xN (0 <= xi <= 1,000,000,000 ).

His C (2 <= C <= N) cows are less than the compartment distribution, and they are angry with the presence of other cows in the cowshed. Farmer John wants to place the cows in a specified compartment to prevent them from fighting each other. The closer they are to each other, the better. So what is the maximum recent distance?

Input/Output Format

Input Format:

 

Row 3: two numbers N and C separated by spaces.

2nd ~ N + 1 rows: each row has an integer representing the coordinates of each compartment.

 

Output Format:

 

The output contains only one row, that is, the maximum closest distance between two adjacent cows.

 

Input and Output sample input sample #1:

5 31 2 8 4 9  

Output sample #1:

3

 

 

Bipartite answer + Partition Method

 

 1 #include<cstdio> 2 #include<algorithm> 3 using namespace std; 4 const int MAXN=100001; 5 inline void read(int &n) 6 { 7     char c=getchar();bool flag=0;n=0; 8     while(c<'0'||c>'9') c=='-'?flag==1,c=getchar():c=getchar(); 9     while(c>='0'&&c<='9')    n=n*10+c-48,c=getchar();10 }11 int n,c;12 int a[MAXN];13 int pd(int val)14 {15     int now=a[1],tot=c-1;16     for(int i=2;i<=n;i++)17         if(a[i]-now>=val)18             now=a[i],tot--;19     if(tot<=0)    return 1;20     else         return 0;21 }22 int main()23 {24     read(n);read(c);25     for(int i=1;i<=n;i++)    read(a[i]);26     sort(a+1,a+n+1);27     int l=0,r=a[n];28     int ans;29     while(l<=r)30     {31         int mid=l+r>>1;32         if(pd(mid))    33             l=mid+1,ans=mid;34         else         35             r=mid-1;36     }37     printf("%d",ans);38     return 0;39 }