Codeforces 767D

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=0,fh=1;char ch=getchar();
    while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();
    if(ch=='-')fh=-1,ch=getchar();
    while(ch<='9'&&ch>='0')res=res*10+ch-'0',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=1,w2=1; tail=0;
    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+1,t=0;
    while (1)
    {
        for (llg i=1;i<=k;i++)
        {
            x--;
            if (x<=0) return 1;
            if (c[x]<t) return 0;
        }
        t++; 
    }
    return 1;
}

int main()
{
    yyj("D");
    cin>>n>>m>>k;
    for (llg i=1;i<=n;i++) scanf("%d",&a[i]);
    sort(a+1,a+n+1,cmp);
    for (llg i=1;i<=m;i++) 
    {
        scanf("%d",&b[i]);
        e[i].val=b[i],e[i].wz=i;
    }
    sort(b+1,b+m+1,cmp);
    sort(e+1,e+m+1,cmpp);
    llg l=0,r=m,mid;
    ans=-1;
    while (l<=r)
    {
        mid=(l+r)>>1;
        if (check(mid)) {ans=mid,l=mid+1;}else r=mid-1;
    }
    cout<<ans<<endl;
    for (llg i=1;i<=ans;i++) printf("%d ",e[i].wz);
    return 0;
}