Codeforces 767D - Cartons of milk

题目链接：http://codeforces.com/contest/767/problem/D

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D比C水系列。

将商店里面的牛奶按照保质期升序排序(显然优先买保质期久的）考虑二分答案，然后再将整个序列归并排序，贪心的检测答案是否正确即可。

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 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #include<vector>
 #include<cstdlib>
 #include<cmath>
 #include<cstring>
 using namespace std;
 #define maxn 2001000
 #define llg int
 #define yyj(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
 llg n,m,a[maxn],b[maxn],c[maxn],ans,tail,k;

 inline llg getint()
 {
     llg res=,fh=;char ch=getchar();
     while((ch<''||ch>'')&&ch!='-')ch=getchar();
     if(ch=='-')fh=-,ch=getchar();
     while(ch<=''&&ch>='')res=res*+ch-'',ch=getchar();
     return res*fh;
 }

 struct node
 {
     llg val,wz;
 }e[maxn];

 bool cmp(llg a,llg b){return a>b;}

 bool cmpp(const node&a,const node&b){return a.val>b.val;}

 inline bool check(llg r2)
 {
     llg r1=n;
     llg w1=,w2=; tail=;
     while (w1<=r1 || w2<=r2)
     {
         if (w1>r1) c[++tail]=b[w2],w2++;
         else if (w2>r2) c[++tail]=a[w1],w1++;
         else if (a[w1]>b[w2])
             {
                  c[++tail]=a[w1],w1++;
             }
             else
             {
                  c[++tail]=b[w2],w2++;
             }
     }
     llg x=tail+,t=;
     while ()
     {
         for (llg i=;i<=k;i++)
         {
             x--;
             if (x<=) return ;
             if (c[x]<t) return ;
         }
         t++;
     }
     return ;
 }

 int main()
 {
     yyj("D");
     cin>>n>>m>>k;
     for (llg i=;i<=n;i++) scanf("%d",&a[i]);
     sort(a+,a+n+,cmp);
     for (llg i=;i<=m;i++)
     {
         scanf("%d",&b[i]);
         e[i].val=b[i],e[i].wz=i;
     }
     sort(b+,b+m+,cmp);
     sort(e+,e+m+,cmpp);
     llg l=,r=m,mid;
     ans=-;
     while (l<=r)
     {
         mid=(l+r)>>;
         if (check(mid)) {ans=mid,l=mid+;}else r=mid-;
     }
     cout<<ans<<endl;
     for (llg i=;i<=ans;i++) printf("%d ",e[i].wz);
     return ;
 }