2019.9.3 number of stars

Topic Portal

Since the subject has the sequence according to the row y

So we scanned according to the order given each star

Because it has not been scanned into the top, so we have to count all scanned x is less than the stars of x

That we renumber all the stars of the abscissa

Set C [x] represents the number renumbering have few stars x

So every time we just count c [1] to c [x] and to

As it relates to each scan the stars have to modify c

So take advantage of Fenwick tree

The Code

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define int long long
using namespace std;
int n,book[15000050],c[1500050],cnt,ans[1500050];
struct node{
    int x,y;
}p[1500050],p1[1500050];
int lowbit(int x)
{
    return x&(-x);
}
bool cmp(node a,node b)
{
    return a.x<b.x;
}
void updata(int i,int x)
{
    int temp=i;
    while(temp<=n)
    {
        c[temp]+=x;
        temp+=lowbit(temp);
    }
}
int query(int i)
{
    int res=0;
    while(i>=1)
    {
        res+=c[i];
        i-=lowbit(i);
    }
    return res;
}
signed main()
{
    scanf("%lld",&n);
    for(int i=1;i<=n;i++)
        scanf("%lld%lld",&p[i].x,&p[i].y),p1[i].x=p[i].x,p1[i].y=p[i].y;
    sort(p1+1,p1+n+1,cmp);
    for(int i=1;i<=n;i++)
        if(!book[p1[i].x])book[p1[i].x]=++cnt;//排序重编号
    for(int i=1;i<=n;i++)
    { 
        UPDATA (Book [P [I] .x], . 1 ); // The statistics on this star 
        ++ ANS [Query (Book [P [I] .x])]; // count prefix and
 //         for (int. 1 = J; J <= n-; J ++) the printf ( "% LLD", C [J]);
 //         the putchar ( '\ n-');
 //         for (int. 1 = J; J <= n-; J ++) the printf ( "% LLD", ANS [J]);
 //         the putchar ( '\ n-'); 
    }
     for ( int I = . 1 ; I <= n-; I ++) the printf ( " % LLD \ n- " , ANS [I]);
     return  0 ; 
}