SGU 119 Beautiful People

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define maxx 100050struct node{    int a,b,id;}g[maxx];int root[maxx];int id[maxx];int len;void output(int x){    if(x==-1)return;    output(root[x]);    printf("%d ",g[x].id);}int cmp (node x,node y){    if(x.a!=y.a)    return x.a<y.a;    return x.b>y.b;}int main(){    int n;    scanf("%d",&n);    for(int i=1;i<=n;i++)    {        scanf("%d%d",&g[i].a,&g[i].b);        g[i].id=i;    }    sort(g+1,g+n+1,cmp);    int len=1;    int l,r;    id[0]=1;    memset(root,-1,sizeof(root));    for(int i=2;i<=n;i++)    {        if(g[i].b>g[id[len-1]].b)        {            id[len++]=i;            root[i]=id[len-2];            continue;        }        l=0;        r=len-1;        while(l<r)        {            int mid=(l+r)>>1;            if(g[i].b>g[id[mid]].b) l=mid+1;            else  r=mid;        }        id[l]=i;        if(l==0)  root[l]=-1;        else  root[i]=id[l-1];    }    printf("%d\n",len);    output(id[len-1]);    puts("");}