POJ2481 Cows

Posted 2020-08-10

题解:

给出n个区间，求每个区间是多少个区间的真子集

按照x从小到大排序，若x相同，则按照y从大到小排序。

然后每次需要判断一下x和y相同的个数，减去就行了

代码:

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<map>
using namespace std;
#define pb push_back
#define mp make_pair
#define se second
#define fs first
#define LL long long
#define CLR(x) memset(x,0,sizeof x)
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1 
typedef pair<int,int> P;
const double eps=1e-9;
const int maxn=100100;
const int mod=1e9+7;
const int INF=1e9;

struct node{
    int s,e,id;
}p[maxn];
int c[maxn],a[maxn];

bool cmp(node a,node b){
    if(a.s==b.s) return a.e>b.e;
    return a.s<b.s;
}

int lowbit(int x){return x&-x;}

void Add(int x,int v){
   while(x<=maxn){
        c[x]+=v;
        x+=lowbit(x);
   }
}

int Sum(int x){
    int sum=0;
    while(x){
        sum+=c[x];
        x-=lowbit(x);
    }
    return sum;
}

int main(){
    int n;
    while(~scanf("%d",&n)&&n){
    CLR(c);
    for(int i=1;i<=n;i++){
        scanf("%d%d",&p[i].s,&p[i].e);
        p[i].s++;
        p[i].e++;
        p[i].id=i;
    }
    sort(p+1,p+n+1,cmp);
    /*
    cout<<endl;
    cout<<endl;
    for(int i=1;i<=n;i++) printf("%d %d %d\n",p[i].s,p[i].e,p[i].id);
    */
    for(int i=1;i<=n;i++){
        int tmp=0,k=i;
        while(k>1&&p[k].e==p[k-1].e&&p[k].s==p[k-1].s){
            tmp++;
            k--;
        } 
        a[p[i].id]=Sum(maxn)-Sum(p[i].e-1)-tmp;
        Add(p[i].e,1);
    }
    for(int i=1;i<=n;i++) printf("%d%c",a[i],(i==n?‘\n‘:‘ ‘));
    }
}