HDU 3265 Posters 线段树 扫描线

把一张海报剩余的部分分割成四个小矩形，然后就是简单的矩形面积并了。

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<sstream>
#include<cmath>
#include<climits>
#include<string>
#include<map>
#include<queue>
#include<vector>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define pb(a) push_back(a)
#define INF 0x1f1f1f1f
#define lson idx<<1,l,mid
#define rson idx<<1|1,mid+1,r
#define PI  3.1415926535898
template<class T> T min(const T& a,const T& b,const T& c) {
    return min(min(a,b),min(a,c));
}
template<class T> T max(const T& a,const T& b,const T& c) {
    return max(max(a,b),max(a,c));
}
void debug() {
#ifdef ONLINE_JUDGE
#else

    freopen("d:\in.txt","r",stdin);
   // freopen("d:\out1.txt","w",stdout);
#endif
}
int getch() {
    int ch;
    while((ch=getchar())!=EOF) {
        if(ch!=' '&&ch!='
')return ch;
    }
    return EOF;
}
const int maxn=201000;
struct Seg
{
    int l,r,x;
    int c;
    Seg(){}
    Seg(int a,int  b,int c,int d):l(a),r(b),x(c),c(d){}
    bool operator < (const Seg& another) const
    {
        return x<another.x;
    }
};
Seg seg[maxn<<1];
int flag[maxn<<3];
int sum[maxn<<3];
int join(int& m,int x1,int y1,int x2,int y2)
{
    seg[m++]=Seg(y1,y2,x1,1);
    seg[m++]=Seg(y1,y2,x2,-1);
    return 0;
}
int PushUp(int idx,int l,int r)
{
    if(flag[idx])
    {
        sum[idx]=r+1-l;
    }else if(l!=r)
        sum[idx]=sum[idx<<1]+sum[idx<<1|1];
    else sum[idx]=0;
    return 0;
}
int build(int idx,int l,int r)
{
    memset(flag,0,sizeof(flag));
    memset(sum,0,sizeof(sum));
    return 0;
}
int update(int idx,int l,int r,int tl,int tr,int v)
{
    if(tl<=l&&tr>=r)
    {
        flag[idx]+=v;
        PushUp(idx,l,r);
        return 0;
    }
    int mid=(r+l)>>1;
    if(tl<=mid)update(lson,tl,tr,v);
    if(tr>mid)update(rson,tl,tr,v);
    PushUp(idx,l,r);
    return 0;
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF&&n)
    {
        int m=0;
        for(int i=0;i<n;i++)
        {
            int x1,x2,x3,x4,y1,y2,y3,y4;
            scanf("%d%d%d%d%d%d%d%d",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4);
            if(x3!=x1)join(m,x1,y1,x3,y4);
            if(y4!=y2)join(m,x1,y4,x4,y2);
            if(x4!=x2)join(m,x4,y3,x2,y2);
            if(y3!=y1)join(m,x3,y1,x2,y3);
        }
        sort(seg,seg+m);
        ll res=0;
        build(1,0,50000);
        for(int i=0;i<m;i++)
        {
            if(i!=0)res+=(ll)(seg[i].x-seg[i-1].x)*sum[1];
            update(1,0,50000,seg[i].l,seg[i].r-1,seg[i].c);
        }
        printf("%I64d
",res);
    }
    return 0;
}