"Hdoj" 1348 Wall

Calculate geometry-convex hull template title, Graham algorithm solution.

1 /*1348*/2#include <iostream>3#include <cstdio>4#include <cstring>5#include <cstdlib>6#include <cmath>7#include <algorithm>8 using namespacestd;9 Ten #defineMAXN 1005 One  Atypedefstructpoint_t { -     Doublex, y; - point_t () {} thepoint_t (DoubleXxDoubleyy) { -x = XX; y =yy; -     } - } point_t; +  - point_t STACK[MAXN]; + point_t POINTS[MAXN]; A Const DoublePI = ACOs (-1.0); at intN; -  - DoubleLength (point_t A, point_t b) { -     returnsqrt ((a.x-b.x) * (a.x-b.x) + (A.Y-B.Y) * (a.y-b.y)); - } -  in DoubleCross (point_t p0, point_t p1, point_t p2) { -     return(p1.x-p0.x) * (P2.Y-P0.Y)-(p2.x-p0.x) * (P1.Y-p0.y); to } +  - BOOLComp (point_t A, point_t b) { the     Doublek = Cross (points[0], A, b); *     return! (k<0|| (k==0&& Length (points[0], a) >length (points[0], b )); $ }Panax Notoginseng  - DoubleGraham () { the     DoubleRET =0; +     intI, J, K; A     inttop; the point_t P0; +      -P0 = points[0]; $K =0; $      for(i=1; i<n; ++i) { -         if(points[i].x<p0.x | | (points[i].x==p0.x && points[i].y<p0.y)) { -P0 =Points[i]; theK =i; -         }Wuyi     } the      -Points[k] = points[0]; Wupoints[0] =P0; -Sort (points+1, points+N, comp); About      $stack[0] = points[0]; -stack[1] = points[1]; -stack[2] = points[2]; -top =2; A      for(i=3; i<n; ++i) { +          while(Cross (stack[top-1], Stack[top], points[i]) <=0&& top>1) the--top; -Stack[++top] =Points[i]; $     } theStack[++top] =P0; the      for(i=1; i<=top; ++i) theRET + = Length (stack[i-1], stack[i]); the      -     returnret; in } the  the intMain () { About     intT; the     intI, J, K, TMP; the     Doublel, ans; the      + #ifndef Online_judge -Freopen ("data.in","R", stdin); the     #endifBayi      thescanf"%d", &t); the      while(t--) { -scanf"%d%lf", &n, &l); -          for(i=0; i<n; ++i) thescanf"%LF%LF", &points[i].x, &points[i].y); theAns =Graham (); theAns + = PI * (l +l); theprintf"%.0lf\n", ans); -         if(t) theprintf"\ n"); the     } the     94     return 0; the}

"Hdoj" 1348 Wall