POJ1151+線段樹+掃描線

/*線段樹+掃描線+離散化求多個矩形的面積*/#include<stdio.h>#include<string.h>#include<stdlib.h>#include<algorithm>#include<iostream>#include<queue>#include<stack>#include<math.h>#include<map>using namespace std;const int maxn = 105;const int maxm = 210;struct SegTree{int l,r;int cover;double L_val,R_val;double sum;}ST[ maxm<<2 ];struct Line{double x,y1,y2;bool InOut;}yLine[ maxm ];int cmp( Line a,Line b ){return a.x<b.x;}double yIndex[ maxm ];int GetIndex( double val,int cnt ){return lower_bound( yIndex,yIndex+cnt,val )-yIndex;}void build( int L,int R,int n ){ST[ n ].l = L;ST[ n ].r = R;ST[ n ].cover = 0;ST[ n ].sum = 0;ST[ n ].L_val = yIndex[ L ];ST[ n ].R_val = yIndex[ R ];if( R-L>1 ){int mid = (L+R)/2;build( L,mid,2*n );build( mid,R,2*n+1 );}}void PushUp( int n ){if( ST[ n ].cover>0 ){ST[ n ].sum = ST[ n ].R_val-ST[ n ].L_val;}else if( ST[ n ].r-ST[ n ].l>1 ){ST[ n ].sum = ST[ 2*n ].sum+ST[ 2*n+1 ].sum;}elseST[ n ].sum = 0;}void update( int left,int right,bool InOut,int n  ){if( left==ST[ n ].l&&right==ST[ n ].r ){if( InOut==true ){ST[ n ].cover++;}else{ST[ n ].cover--;}}else {int mid = (ST[ n ].l+ST[ n ].r)/2;if( mid>=right ) update( left,right,InOut,2*n );else if( mid<=left ) update( left,right,InOut,2*n+1 );else {update( left,mid,InOut,2*n );update( mid,right,InOut,2*n+1 );}}PushUp( n );}int main(){int n;int T = 1;while( scanf("%d",&n)==1,n ){printf("Test case #%d\n",T++);double x1,y1,x2,y2;int cnt = 0;for( int i=0;i<n;i++ ){scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);yLine[ 2*i ].x = x1;yLine[ 2*i+1 ].x = x2;yLine[ 2*i ].y1 = yLine[ 2*i+1 ].y1 = y1;yLine[ 2*i ].y2 = yLine[ 2*i+1 ].y2 = y2;yLine[ 2*i ].InOut = true;yLine[ 2*i+1 ].InOut = false;yIndex[ 2*i ] = y1;yIndex[ 2*i+1 ] = y2;}sort( yLine,yLine+2*n,cmp );sort( yIndex,yIndex+2*n );for( int i=1;i<2*n;i++ ){if( yIndex[i]!=yIndex[i-1] )yIndex[ cnt++ ] = yIndex[ i-1 ];}yIndex[ cnt++ ] = yIndex[ 2*n-1 ];build( 0,cnt-1,1 );double res = 0;update( GetIndex( yLine[0].y1,cnt ),GetIndex( yLine[0].y2,cnt ),yLine[0].InOut,1 );for( int i=1;i<2*n;i++ ){res += ST[ 1 ].sum*( yLine[i].x-yLine[i-1].x );update( GetIndex( yLine[i].y1,cnt ),GetIndex( yLine[i].y2,cnt ),yLine[i].InOut,1 );}printf("Total explored area: %.2lf\n\n",res);}return 0;}