P1325 Radar Installation

Transmission DoorIdeas:

Take the greedy thought.

Consider each island as a center, with the radar range D as the radius, to find the x-axis of the left and right two intersections, the two intersections sandwiched between the need to place a radar, so that the problem is converted to an interval to pick points. When enumerating islands, record the location of the last radar before LAS, if the island is within the range of the radar, skip it, otherwise, place a radar at the right end of the area where the island is located.

　　For the code to look good, I hit a huge structure.

Main function Section:

intMain () {n=T.RESD ();d =T.read ();  for(LL i=1; i<=n;i++) {t[i].x=t.read (), t[i].y=T.read (); T[I].L=t.deal_l (T[I].X,T[I].Y);//calculates the left end of the intervalT[i].r=t.deal_r (T[I].X,T[I].Y);//calculates the right endpoint of the interval} sort (T+1, t+n+1, CMP);//Sort by interval right endpointlas=t[1].r;ans++;//Place the first radar, record the location of Las     for(LL i=2; i<=n;i++) {dis=t.dist (T[i].x,t[i].y,las,0);//calculates the distance between the island and the last radar placed before it        if(Dis<=d)Continue;Elselas=t[i].r,ans++;//if not within the radar range, place a radar at the right end of the interval and update the LAS. } printf ("%lld\n", ans); return 0; }

Full code:

#include <iostream>#include<cstdio>#include<algorithm>#include<cmath>#include<cstring>#include<string>#include<cstdlib>#include<stack>#include<vector>#include<queue>#include<deque>#include<map>#include<Set>using namespacestd;#defineMax (a) (a) > (b)? ( A):(B))#defineMin (a) < (b) ( A):(B))#defineMAXN 2001typedefLong LongLL; LL N,ans;DoubleD,las,dis;structhh{DoubleX,y,l,r;BOOLBo; InlineDoubleRead () {DoubleLS;SCANF ("%LF", &ls);returnls; } inline ll resd () {ll xs=0, kr=1;Charls; LS=GetChar ();  while(!isdigit (LS)) {            if(! (ls^ $)) KR=-1; LS=GetChar (); }         while(IsDigit (LS)) {xs= (xs<<1) + (xs<<3) + (ls^ -); LS=GetChar (); }        returnxs*KR; } InlineDoubledeal_l (DoubleADoubleb) {returnA-SQRT (d*d-b*b); } InlineDoubleDeal_r (DoubleADoubleb) {returnA+SQRT (d*d-b*b); } InlineDoubleDistDoubleA1,DoubleB1,DoubleA2,DoubleB2) {        returnsqrt ((A1-A2) * (A1-A2) + (B1-B2) * (b1-B2)); }}t[maxn],t;inlineBOOLcmpConstHh&a,Consthh&b) {    returna.r<B.R;}intMain () {n=T.RESD ();d =T.read ();  for(LL i=1; i<=n;i++) {t[i].x=t.read (), t[i].y=T.read (); T[I].L=t.deal_l (T[I].X,T[I].Y); T[I].R=T.deal_r (T[I].X,T[I].Y); } sort (T+1, t+n+1, CMP); Las=t[1].r;ans++;  for(LL i=2; i<=n;i++) {dis=t.dist (T[i].x,t[i].y,las,0); if(Dis<=d)Continue; Elselas=t[i].r,ans++; } printf ("%lld\n", ans);return 0;}

P1325 Radar Installation