POJ1113 Wall Convex bag

The main idea: building a fence around the castle, requiring the fence at least from the Castle L, the corner with an arc to replace, seeking the length of the fence.

Topic idea: fence length = convex hull circumference + (2*pi*l), also do not know why C++POJ will re,g++ no problem.

#include <cstdio>#include<cstdlib>#include<cmath>#include<iostream>#include<algorithm>#include<cstring>#include<vector>#include<queue>#defineINF 0x3f3f3f3f#defineMAX 100005#definePI ACOs (-1)using namespacestd;structnode{intx, y;} Point[max];intStuck[max],n,l,top;BOOLcmpstructNode A,structnode B) {    if(A.y <b.y)return true; if(A.y==b.y && a.x<b.x)return true; return false;}intCross (intX1,intY1,intX2,intY2,intX3,inty3) {    return(x1-x2) * (y1-y3)-(X1-X3) * (y1-y2);}voidGraham () {memset (Stuck,0,sizeof(Stuck)); stuck[0]=0; stuck[1]=1; Top=1;  for(intI=2; i<n;i++)    {         while(top>0&& Cross (point[stuck[top]].x,point[stuck[top]].y,point[stuck[top-1]].x,point[stuck[top-1]].Y,POINT[I].X,POINT[I].Y) <=0) Top--; stuck[++top]=i; }    intlen=top; stuck[++top]=n-2;  for(inti=n-3; i>=0; i--)    {         while(Top!=len && Cross (point[stuck[top]].x,point[stuck[top]].y,point[stuck[top-1]].x,point[stuck[top-1]].Y,POINT[I].X,POINT[I].Y) <=0) Top--; stuck[++top]=i; }}DoubleDist (intPOS1,intPos2) {    returnsqrt ((point[pos1].x-point[pos2].x) * (point[pos1].x-point[pos2].x) *1.0+ (POINT[POS1].Y-POINT[POS2].Y) * (point[pos1].y-point[pos2].y));}intMain () {intK;  while(SCANF ("%d%d", &n,&l)! =EOF) {k=0;  for(intI=0; i<n;i++) {scanf ("%d%d",&point[i].x,&point[i].y); if(Point[k].y > Point[i].y | | (point[k].x>point[i].x && point[k].y==point[i].y)) K=i; } Swap (point[0],point[k]); Sort ( point+1, point+n,cmp);        Graham (); Doublesum=0; Sum+=dist (stuck[0],stuck[top]) +2*pi*l;  for(intI=1; i<=top;i++) Sum+=dist (stuck[i],stuck[i-1]); intAns= (int) (sum+0.5); printf ("%d\n", ans); }    return 0;}

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POJ1113 Wall Convex bag