CF#The Union of k-Segments -离散化+树状数组

真是写得太挫了。。

离散化+树状数组

  3S。。。

#include <cstdio>#include <cmath>#include <cstring>#include <string>#include <algorithm>#include <queue>#include <map>#include <stack>#include <vector>#include <iostream>using namespace std;struct node{    int l,r;    node(){}    node(int a,int b){l=a,r=b;}};const int N=1000005*4;    int n,k;node tm[1000005];int cmp(node a,node b){    return a.l<b.l;}map <int ,int > to_num;map <int ,int > to_val;int tmp_num[N];int tree[N];int lowbit(int x){    return x&-x;}void add(int x,int value){    for (int i=x;i<=4000000;i=i+lowbit(i))    {        tree[i]+=value;    }}int get(int x){    int sum=0;    for (int i=x;i;i-=lowbit(i))    {        sum+=tree[i];    }    return sum;}int pos[N];int main(){         int i;     cin>>n>>k;    int ok=0;    for (i=1;i<=n;i++)    {        scanf("%d%d",&tm[i].l,&tm[i].r);        tmp_num[ok++]=tm[i].l;        tmp_num[ok++]=tm[i].r;    }    sort(tmp_num,tmp_num+ok);    int len=0;    for (i=0;i<ok;i++)    {        if (i==0)        {            tmp_num[len++]=tmp_num[i];        }        else            if (tmp_num[i]==tmp_num[i-1])                continue;            else                tmp_num[len++]=tmp_num[i];    }    int tol=1;    for (i=0;i<len;i++)    {        to_num[tmp_num[i]]=tol;          to_val[tol]=tmp_num[i];          tol+=2;    }    for (i=1;i<=n;i++)    {        int tmpx=to_num[tm[i].l];        int tmpy=to_num[tm[i].r];        add(tmpx,1);        add(tmpy+1,-1);    }    for (i=1;i<=4000000;i++)    {        int x=get(i);        if (x>=k)            pos[i]=1;    }        int sum=0;    int last;    int line=1;    for (i=1;i<=4000000+2;i++)    {                if (pos[i]==1&&line)            last=i,line=0;        if (pos[i]==1)            continue;        if (pos[i]==0&&pos[i-1]==1)        {             tm[++sum]=node(to_val[last],to_val[i-1]);            last=i;line=1;        }    }    printf("%d\n",sum);    for (i=1;i<=sum;i++)    {        printf("%d %d\n",tm[i].l,tm[i].r);    }                   return 0;    }