[poj] 2828 Buy Tickets

#include<cstdio>
#define N 200010
using namespace std;
int n,pos[N],nm[N];
struct hhh
{
    int l,r,data,sum;
}tre[4*N];

int read()
{
    int ans=0,fu=1;
    char j=getchar();
    for (;(j<‘0‘ || j>‘9‘) && j!=‘-‘;j=getchar()) ;
    if (j==‘-‘) fu=-1,j=getchar();
    for (;j>=‘0‘ && j<=‘9‘;j=getchar()) ans*=10,ans+=j-‘0‘;
    return ans*fu;
}

void build(int i,int l,int r)
{
    tre[i].l=l;
    tre[i].r=r;
    tre[i].data=0;
    tre[i].sum=r-l+1;
    if (l==r) return ;
    build(i*2,l,(l+r)>>1);
    build(i*2+1,((l+r)>>1)+1,r);
    tre[i].sum=tre[i*2].sum+tre[i*2+1].sum;
}

void modify(int i,int x,int y)
{
    if (tre[i].l==tre[i].r)
    {
    tre[i].data=y;
    tre[i].sum=0;
    return ;
    }
    if (tre[i*2].sum<x) modify(i*2+1,x-tre[i*2].sum,y);
    else modify(i*2,x,y);
    tre[i].sum=tre[i*2].sum+tre[i*2+1].sum;
}

int query(int i,int x)
{
    if (tre[i].l==tre[i].r) return tre[i].data;
    int mid=(tre[i].l+tre[i].r)>>1;
    if (x>mid) return query(i*2+1,x);
    else return query(i*2,x);
}

int main()
{
    while (~scanf("%d",&n))
    {
    build(1,1,n);
    for (int i=1;i<=n;i++)
    {
        pos[i]=read();
        nm[i]=read();
    }
    for (int i=n;i>=1;i--)
        modify(1,pos[i]+1,nm[i]);
    for (int i=1;i<=n;i++)
        printf("%d%c",query(1,i)," \n"[i==n]);
    }
    return 0;
}