poj 2456 Aggressive cows 整数二分写法模板题-白红宇

poj 2456 Aggressive cows 整数二分写法模板题

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发布时间：2019-05-25

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Aggressive cows

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 9129		Accepted: 4547

Description

Farmer John has built a new long barn, with N (2 <= N <= 100,000) stalls. The stalls are located along a straight line at positions x1,...,xN (0 <= xi <= 1,000,000,000).

His C (2 <= C <= N) cows don't like this barn layout and become aggressive towards each other once put into a stall. To prevent the cows from hurting each other, FJ want to assign the cows to the stalls, such that the minimum distance between any two of them is as large as possible. What is the largest minimum distance?

Input

* Line 1: Two space-separated integers: N and C

* Lines 2..N+1: Line i+1 contains an integer stall location, xi

Output

* Line 1: One integer: the largest minimum distance

Sample Input

5 312849

Sample Output

Hint

OUTPUT DETAILS:

FJ can put his 3 cows in the stalls at positions 1, 4 and 8, resulting in a minimum distance of 3.

Huge input data,scanf is recommended.

Source

分析：注意分析区间的开闭性

#include
     
       #include 
      
        #include 
       
         #include 
        
          #include 
         
           #include 
          
            #include 
           
             #include 
            
              #include 
             
               #include 
              
                using namespace std; #define MM(a) memset(a,0,sizeof(a)) typedef long long LL; typedef unsigned long long ULL; const int mod = 1000000007; const double eps = 1e-10; const int inf = 0x3f3f3f3f; int x[100005]; int n,m,maxn; int ok(int d) { int p=x[1],cnt=1; for(int i=2;i<=n;i++) if(x[i]-p>=d) { p=x[i]; cnt++; if(cnt>=m) return 1; } return 0; } int main() { while(~scanf("%d %d",&n,&m)) { maxn=0; for(int i=1;i<=n;i++) { scanf("%d",&x[i]); if(x[i]>maxn) maxn=x[i]; } sort(x+1,x+n+1); int l=0,r=maxn+1,mid; while(r-l>1) { mid=(l+r)/2; if(ok(mid)) l=mid; else r=mid; } printf("%d\n",l); //左闭右开区间，输出l； } return 0; }

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