【CodeForces 604B】F - 一般水的题1-More Cowbe
Description
Kevin Sun wants to move his precious collection of n cowbells from Naperthrill to Exeter, where there is actually grass instead of corn. Before moving, he must pack his cowbells into k boxes of a fixed size. In order to keep his collection safe during transportation, he won't place more than two cowbells into a single box. Since Kevin wishes to minimize expenses, he is curious about the smallest size box he can use to pack his entire collection.
Kevin is a meticulous cowbell collector and knows that the size of his i-th (1 ≤ i ≤ n) cowbell is an integer si. In fact, he keeps his cowbells sorted by size, so si - 1 ≤ si for any i > 1. Also an expert packer, Kevin can fit one or two cowbells into a box of size s if and only if the sum of their sizes does not exceed s. Given this information, help Kevin determine the smallest s for which it is possible to put all of his cowbells into k boxes of size s.
Input
The first line of the input contains two space-separated integers n and k (1 ≤ n ≤ 2·k ≤ 100 000), denoting the number of cowbells and the number of boxes, respectively.
The next line contains n space-separated integers s1, s2, ..., sn (1 ≤ s1 ≤ s2 ≤ ... ≤ sn ≤ 1 000 000), the sizes of Kevin's cowbells. It is guaranteed that the sizes si are given in non-decreasing order.
Output
Print a single integer, the smallest s for which it is possible for Kevin to put all of his cowbells into k boxes of size s.
Sample Input
2 5
2 3 5 9
3 5 7
Hint
In the first sample, Kevin must pack his two cowbells into the same box.
In the second sample, Kevin can pack together the following sets of cowbells: {2, 3}, {5} and {9}.
In the third sample, the optimal solution is {3, 5} and {7}.
题意是给n个牛铃和k个箱子,每个箱子可以装1~2个牛铃,每个牛铃大小不同,所有箱子都是s容量,求最小的s可以装所有的牛铃。
贪心,读入的数据已经排好,将k个牛铃放进k个箱子,每个箱子一个,那么还有n-k个牛铃必须放到已经装有1个的箱子里,那么就有n-k个箱子是装两个的。我们让只装一个牛铃的箱子尽量装大的,要装两个的箱子,装最小的(n-k)*2个里面最大的和最小的,第二大和第二小……
#include<stdio.h> #include<algorithm> using namespace std; long long n,k,s[100005],maxs; int main(){ scanf("%lld%lld",&n,&k); for(long long i=0;i<n;i++) scanf("%lld",&s[i]); maxs=s[n-1]; for(long long i=0;i<n-k;i++) maxs=max(maxs,s[i]+s[(n-k)*2-i-1]); printf("%lld\n",maxs); return 0; }
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