poj1151 Atlantis(线段树+扫描线+离散化，求矩形面积并)

写过的裸题，还敲了半天。。。太蒻

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define ll long long#define inf 0x3f3f3f3f#define N 220int n,m,num;double aa[N],ans;struct Lines{    double x,y1,y2;bool f;//0--del 1--add}a[N];inline bool cmp(Lines x,Lines y){    return x.x==y.x?x.f>y.f:x.x<y.x;}struct node{    double len,clen;int cov;}tree[N<<2];inline void pushup(int p){    if(tree[p].cov) tree[p].clen=tree[p].len;    else tree[p].clen=tree[p<<1].clen+tree[p<<1|1].clen;}void build(int p,int l,int r){    tree[p].cov=0;tree[p].clen=0;    if(l==r){tree[p].len=aa[l+1]-aa[l];return;}    int mid=l+r>>1;    build(p<<1,l,mid);build(p<<1|1,mid+1,r);    tree[p].len=tree[p<<1].len+tree[p<<1|1].len;}void change(int p,int l,int r,int x,int y,int val){    if(x<=l&&r<=y){        tree[p].cov+=val;        if(tree[p].cov==1) tree[p].clen=tree[p].len;        if(tree[p].cov==0){            if(l==r) tree[p].clen=0;            else pushup(p);        }return;    }    int mid=l+r>>1;    if(x<=mid) change(p<<1,l,mid,x,y,val);    if(y>mid) change(p<<1|1,mid+1,r,x,y,val);    pushup(p);}int main(){//  freopen("a.in","r",stdin);    for(int tst=1;;tst++){        scanf("%d",&n);if(!n) break;        if(tst!=1) puts("");m=0;num=0;ans=0;        printf("Test case #%d\n",tst);        for(int i=1;i<=n;++i){            double x1,y1,x2,y2;            scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);            a[++num].x=x1;a[num].y1=y1;a[num].y2=y2;a[num].f=1;            a[++num].x=x2;a[num].y1=y1;a[num].y2=y2;a[num].f=0;            aa[++m]=y1;aa[++m]=y2;        }sort(a+1,a+num+1,cmp);        sort(aa+1,aa+m+1);m=unique(aa+1,aa+m+1)-aa-1;build(1,1,m-1);        for(int i=1;i<=num;++i){            ans+=(a[i].x-a[i-1].x)*tree[1].clen;            change(1,1,m-1,lower_bound(aa+1,aa+m+1,a[i].y1)-aa,lower_bound(aa+1,aa+m+1,a[i].y2)-aa-1,a[i].f?1:-1);        }        printf("Total explored area: %.2lf\n",ans);    }    return 0;}