CF_604B(二分+贪心)

#include<iostream>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<stdio.h>
#include<math.h>
using namespace std;
int bell[1000000+100];
int n;
bool kefou(int rong,int tou,int wei,int k)
{
int i,q,w;
int ge=0;
for(w=wei,i=1;;)
{
if(w<i)break;
if(bell[w]+bell[i]<=rong)
{
w-=1;
i+=1;
ge+=1;
continue;
}
else
{
w-=1;
ge+=1;
continue;
}
}
if(ge<=k)return 1;
return 0;
}

int binary(int k)
{
int high=0xfffffff,low=bell
;
int midle;
while(high>=low)
{
midle=(high+low)/2;
if(kefou(midle,1,n,k)==1&&kefou(midle-1,1,n,k)==0)break;
if(kefou(midle,1,n,k))high=midle-1;
else low=midle+1;
}
return midle;
}

int main()
{
int k;
while(scanf("%d%d",&n,&k)!=EOF)
{
int i,q,w;
for(i=1;i<=n;i++)
{
scanf("%d",&bell[i]);
}

int result=binary(k);
printf("%d\n",result);
}
return 0;
}