POJ2456-Aggressive cows

Aggressive cows

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 14024 Accepted: 6798

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

3

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

USACO 2005 February Gold

题意：有n个牛舍和c头牛，让c头牛住进牛舍，问任意两头牛之间最近距离最大为多少

解题思路：给n个牛舍进行排序，然后二分

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <algorithm>#include <cmath>#include <map>#include <cmath>#include <set>#include <stack>#include <queue>#include <vector>#include <bitset>#include <functional>using namespace std;#define LL long longconst int INF=0x3f3f3f3f;int n,k;int a[100050];bool check(int x){    int sum=1,xx=a[1];    for(int i=2;i<=n;i++)    {        if(a[i]-xx>=x) sum++,xx=a[i];        if(sum>=k) break;    }    if(sum>=k) return 1;    else return 0;}int main(){while(~scanf("%d%d",&n,&k))    {        for(int i=1;i<=n;i++) scanf("%d",&a[i]);        sort(a+1,a+1+n);        int l=0,r=INF,ans;        while(l<=r)        {            int mid=(l+r)>>1;            if(check(mid)) {l=mid+1,ans=mid;}            else r=mid-1;        }        printf("%d\n",ans);    }return 0;}