bzoj1293: [SCOI2009]生日礼物 单调队列

#include<cstdio>
#include<algorithm>
#include<cstring>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
const int N=1e6+5;
int n,m,k;
struct node
{
int x,y;
}a
;
int q
,num
;
bool cmp(node a,node b)
{
return a.x<b.x;
}
int main()
{
scanf("%d%d",&n,&k);
int tot=0;
fo(i,1,k)
{
int x;
scanf("%d",&x);
fo(j,1,x)
{
int y;
scanf("%d",&y);
a[++tot].x=y,a[tot].y=i;
}
}
sort(a+1,a+1+tot,cmp);
int t=1,w=0,ans=1e9;
fo(i,1,tot)
{
q[++w]=i;num[a[i].y]++;
while (t<=w&&num[a[q[t]].y]>1)num[a[q[t++]].y]--;
bool flag=0;
fo(j,1,k)if (!num[j])flag=1;
if(!flag)ans=min(ans,a[q[w]].x-a[q[t]].x);
}
printf("%d\n",ans);
return 0;
}