POJ 2352-Stars(线段树)

标签：

Stars

Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

Submit Status Practice POJ 2352

Appoint description:  System Crawler  (2015-04-14)

Description

Astronomers often examine star maps where stars are represented by points on a plane and each star has Cartesian coordinates. Let the level of a star be an amount of the stars that are not higher and not to the right of the given star. Astronomers want to know the distribution of the levels of the stars. 

For example, look at the map shown on the figure above. Level of the star number 5 is equal to 3 (it‘s formed by three stars with a numbers 1, 2 and 4). And the levels of the stars numbered by 2 and 4 are 1. At this map there are only one star of the level 0, two stars of the level 1, one star of the level 2, and one star of the level 3. 

You are to write a program that will count the amounts of the stars of each level on a given map.

Input

The first line of the input file contains a number of stars N (1<=N<=15000). The following N lines describe coordinates of stars (two integers X and Y per line separated by a space, 0<=X,Y<=32000). There can be only one star at one point of the plane. Stars are listed in ascending order of Y coordinate. Stars with equal Y coordinates are listed in ascending order of X coordinate. 

Output

The output should contain N lines, one number per line. The first line contains amount of stars of the level 0, the second does amount of stars of the level 1 and so on, the last line contains amount of stars of the level N-1.

Sample Input

5
1 1
5 1
7 1
3 3
5 5

Sample Output

1
2
1
1
0

Hint

This problem has huge input data,use scanf() instead of cin to read data to avoid time limit exceed.

思路：用线段树维护一下每一个横坐标出现的次数。

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <set>
#include <queue>
#include <stack>
#include <map>
using namespace std;
typedef long long LL;
const int inf=0x3f3f3f3f;
const double pi= acos(-1.0);
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int MAXN=15000+10;
struct node
{
    int x;
    int y;
}q[MAXN<<2];
int sum[MAXN<<4];
int cnt[MAXN<<4];
int cmp(struct node a,struct node b)
{
    if(a.y!=b.y)
        return a.y<b.y;
    else if(a.y==b.y)
        return a.x<b.x;
}
void PushUp(int rt)
{
    sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}

void Update(int p,int l,int r,int rt)
{
    if(l==r){
        sum[rt]++;
        return ;
    }
    int mid=(l+r)>>1;
    if(p<=mid)
        Update(p,lson);
    else
        Update(p,rson);
    PushUp(rt);
}

int Query(int ll,int rr,int l,int r,int rt)
{
    if(ll<=l&&rr>=r){
        return sum[rt];
    }
    int mid=(l+r)>>1;
    int ans=0;
    if(ll<=mid)
        ans+=Query(ll,rr,lson);
    if(rr>mid)
        ans+=Query(ll,rr,rson);
    return ans;

}

int main()
{
    int n,i;
    scanf("%d",&n);
    int maxx=-inf;
    memset(sum,0,sizeof(sum));
    for(i=0;i<n;i++){
        scanf("%d %d",&q[i].x,&q[i].y);
        maxx=max(maxx,q[i].x);
    }
    sort(q,q+n,cmp);
    memset(cnt,0,sizeof(cnt));
    int ans;
    for(i=0;i<n;i++){
        ans=Query(0,q[i].x,0,maxx,1);
        Update(q[i].x,0,maxx,1);
        cnt[ans]++;
    }
    for(i=0;i<n;i++){
        printf("%d\n",cnt[i]);
    }
    return 0;
}

POJ 2352-Stars(线段树)

标签：

原文地址：http://blog.csdn.net/u013486414/article/details/45067719