1P5: Earthquake!

Question

USGS's seismometers have just detected a major earthquake! Emergency response teams need a quick estimate of the number of people affected. Write a program to compute this estimate.

Your program receives 2 inputs. The first is the details of the earthquake itself. The earthquake modeled as a line segment along which the earth ruptured, along with the critical distance from the fault within which damage could be expected. The second input is a list of the location and population of cities in the area. Your program should compute the number of people living in the affected area, that is the sum of the population of all cities within the critical distance of the fault segment.

Input

First a line describing the earthquake, containing the x,y coordinates of the start and end points of the fault, plus the critical distance. The format is A_x A_y B_x B_y D. For example:

3.0 3.0 7.0 4.0 2.5

encodes the fault extending from (3.0,3.0) to (7.0,4.0) and a critical distance of 2.5.

Second, one line per city in the area, containing the x,y coordinates of the city and its population. For example:

1.0 1.0 2500
5.0 7.0 8000
3.0 4.0 7500
9.0 6.0 3000
4.0 2.0 1000

Output

The number of people living in the affected area. For the above example only the third and fifth cities are in the danger area, so the output would be

8500

Shortest code wins.

Example 2

0.0 0.0 10.0 0.0 5.0
5.0 4.0 10000
5.0 -4.0 1000
5.0 6.0 100
11.0 2.0 10 
-4.0 4.0 1

generates

11010

Answer 1

Ruby, 171 152 155 153

u,v,a,b,d=gets.split.map &:to_f
a-=u;b-=v
p eval$<.map{|l|"(x=%f-u;t=(a*x+b*y=%f-v)/(a*a+b*b);d*d<(x-a*t=t<0?0:t>1?1:t)**2+(y-t*b)**2?0:%d)"%l.split}*'+'

This is my first ruby submission and my first code-golf at all. Straight forward implementation of the task. Please give me some hints how to improve (there must be a shorter way to read floats...).

Answer 2

Javascript (437)

This can probably be golfed significantly, but not enough to beat the Ruby solution.

p=$("#i").text().split("\n");for(i=0;i<p.length;i++){p[i]=p[i].split(" ")}
z=p[0];a=z[0];b=z[1];c=z[2];d=z[3];e=z[4];o=0;f=[a,b];g=[c,d];
function q(r,s){return Math.sqrt(Math.pow(s[0]-r[0],2)+Math.pow(s[1]-r[1],2))}
for(i=1;i<p.length;i++){w=p[i];u=((w[0]-a)*(c-a)+(w[1]-b)*(d-b))/Math.pow(q(f,g,2),2);
x=[(a*1)+u*(c-a),(b*1)+u*(d-b)];l=e;m=w[2]*1;u=w[0];w=w[1];v=[u,w];
o+=q(v,x)<l&&q(x,g)+q(x,f)==q(f,g)?m:q(v,f)<l?m:q(v,g)<l?m:0}alert(o);

You can see it in action here.

Answer 3

C# - 743 715

namespace System{using Linq;using m=Math;class P{public float X,Y;}class E{static void Main(){Func<string,float>p=s=>float.Parse(s);Func<P,P,double>d=(a,b)=>{return a.X*b.X+a.Y*b.Y;},c=(a,b)=>{return a.X*b.Y-a.Y*b.X;};Func<P,P,P>u=(a,b)=>{return new P{X=a.X-b.X,Y=a.Y-b.Y};};Func<P,P,P,double>g=(A,B,C)=>{return d(u(C,B),u(B,A))>0?m.Sqrt(d(u(B,C),u(B,C))):d(u(C,A),u(A,B))>0?m.Sqrt(d(u(A,C),u(A,C))):m.Abs(c(u(B,A),u(C,A))/m.Sqrt(d(u(B,A),u(B,A))));};var n=IO.File.ReadAllLines("i");var i=n[0].Split();var q=new{A=new P{X=p(i[0]),Y=p(i[1])},B=new P{X=p(i[2]),Y=p(i[3])},D=p(i[4])};Console.WriteLine((from l in n.Skip(1)let f=l.Split()let w=new P{X=p(f[0]),Y=p(f[1])}where g(q.A,q.B,w)<q.D select p(f[2])).Sum());}}}

Non-Golfed:

namespace System
{
    using Linq;
    using m = Math;
    class Point { public float X, Y;}
    class Earthquake
    {
        static void Main()
        {
            Func<string, float> parse = s => float.Parse(s);
            Func<Point, Point, double> dotProduct = (a, b) => { return a.X * b.X + a.Y * b.Y; }, 
                                       crossProduct = (a, b) => { return a.X * b.Y - a.Y * b.X; };
            Func<Point, Point, Point> subtract = (a, b) => { return new Point { X = a.X - b.X, Y = a.Y - b.Y }; };
            Func<Point, Point, Point, double> getDistance = (A, B, C) => { 
                return dotProduct(subtract(C, B), subtract(B, A)) > 0 ? 
                        m.Sqrt(dotProduct(subtract(B, C), subtract(B, C))) : 
                        dotProduct(subtract(C, A), subtract(A, B)) > 0 ? 
                            m.Sqrt(dotProduct(subtract(A, C), subtract(A, C))) : 
                            m.Abs(crossProduct(subtract(B, A), subtract(C, A)) / m.Sqrt(dotProduct(subtract(B, A), subtract(B, A)))); 
            };
            var inputLines = IO.File.ReadAllLines("i"); 
            var quakeLine = inputLines[0].Split(); 
            var quake = new { 
                PointA = new Point { X = parse(quakeLine[0]), Y = parse(quakeLine[1]) }, 
                PointB = new Point { X = parse(quakeLine[2]), Y = parse(quakeLine[3]) }, 
                Distance = parse(quakeLine[4]) 
            };
            var affectedPopulations = (from line in inputLines.Skip(1) 
                                       let fields = line.Split() 
                                       let location = new Point { X = parse(fields[0]), Y = parse(fields[1]) } 
                                       let population = parse(fields[2])
                                       where getDistance(quake.PointA, quake.PointB, location) < quake.Distance 
                                       select population);
            Console.WriteLine(affectedPopulations.Sum());
        }
    }
}

Answer 4

c -- 471 characters

#include <stdio.h>
#define F float
#define G getline(&v,&l,stdin)
F a[2],b[2],c[2],d[2],e[2],r,t,y,z;char*v;size_t l,n,p;
F s(F u[2],F v[2]){y=u[0]-v[0];z=u[1]-v[1];return y*y+z*z;}
j(F g[2],F h[2],F i[2]){*i=*g-*h;i[1]=g[1]-h[1];}
int i(){j(b,a,d);j(c,a,e);t=*d**e+d[1]*e[1];
return s(a,c)<=r||s(b,c)<=r||t>0&&t/s(a,b)<=1&&s(a,c)-t*t/s(a,b)<=r;}
int main(){G;sscanf(v,"%f %f %f %f %f",a,a+1,b,b+1,&r);r*=r;
while(G!=-1)sscanf(v,"%f %f %i",c,c+1,&p),n+=p*i();printf("%d\n",n);}

It assumes your standard library has getline.

The method is clarified a bit in the comment to the ungolfed version:

#include <stdio.h>

float a[2],b[2],c[2],d[2],e[2],r,t,y,z;
char*v;
size_t l,n,p;
float s(float u[2],float v[2]){ /* returns the square of the distance
                   between two points */
  y=u[0]-v[0];
  z=u[1]-v[1];
  return y*y+z*z;
}
j(float g[2],float h[2],float i[2]){ /* sets i=g-h */
  i[0]=g[0]-h[0];
  i[1]=g[1]-h[1];
}
int i/*sCLose*/(){
  j(b,a,d); /* d=b-a */
  j(c,a,e); /* e=c-a */
  t=d[0]*e[0]+d[1]*e[1]; /* dot product */ 
  return 
    (s(a,c)<=r) || /* near one end point */
    (s(b,c)<=r) || /* near the other */
    (  
     (t>0) && /* C lies more "towards" B than away */
     (t/s(a,b)<=1) && /* Nearest point on AB to C lies between A and B */
     (s(a,c)-t*t/s(a,b)<=r) /* length of the altitude less than R */
       ); 
}
int main(){
  getline(&v,&l,stdin);
  sscanf(v,"%f %f %f %f %f",a,a+1,b,b+1,&r);
  r*=r; /* r is now r squared, as that is the only way we use it */
  printf("(%f, %f); (%f, %f): %f\n",a[0],a[1],b[0],b[1],r);
  while (getline(&v,&l,stdin) != -1){
    sscanf(v,"%f %f %i",c,c+1,&p);
    printf("\t (%f, %f): %d\n",c[0],c[1],p);
    n+=p*i/*sClose*/();
  }
  printf("%d\n",n);
}

Answer 5

scala: 660 chars:

object E extends App{
type I=Int
type D=Double
def b(h:D,i:D,x:I,y:I,d:D)=(x-h)*(x-h)+(y-i)*(y-i)<=d*d
def a(p:java.awt.Polygon,x:I,y:I,h:I,i:I,d:D,r:Array[String])={
val w=r(0).toDouble
val j=r(1).toDouble
val n=r(2).toInt
if (p.contains(w,j)||b(j,w,x,y,d)||b(j,w,i,h,d))n
else 0}
val s=new java.util.Scanner(System.in)
val b=s.nextLine.split(" ")
val c=b.map(_.toDouble)
val e=c.map(_.toInt)
val(x,h,y,i,d)=(e(0),e(2),e(1),e(3),c(4))
val f=List(x,h)
val g=List(y,i)
val p=new java.awt.Polygon((f:::f.reverse).toArray,(g.map(_-e(4)):::g.reverse.map(_+e(4))).toArray,4)
var r=0
while(s.hasNext){
val row=s.nextLine
r+=a(p,x,y,h,i,d,row.split(" "))}
println(r)}

ungolfed:

object Earthquake extends App {

  def bowContains (h: Double, i: Double, x:Int, y:Int, d: Double) : Boolean = {
    (x-h)*(x-h) + (y-i)*(y-i) <= d*d
  }

  import java.awt._    

  def affected (polygon: Polygon, x:Int, y:Int, h: Int, i: Int, d: Double, row: Array[String]) : Int = {
    val w = row (0).toDouble 
    val j = row (1).toDouble 
    val population = row (2).toInt
    if (polygon.contains (w, j) || bowContains (j, w, x, y, d) || bowContains (j, w, i, h, d))
      population 
    else 0 
  }
  val sc = new java.util.Scanner (System.in)
  val line = sc.nextLine.split (" ")

  val li = line.map (_.toDouble)
  val ll = li.map (_.toInt)

  val (x, h, y, i, d) = (ll (0), ll (2), ll (1), ll (3), li(4))
  val xs = List (x, h)
  val ys = List (y, i)
  
  val polygon = new Polygon ((xs ::: xs.reverse).toArray, (ys.map (_ - ll(4)) ::: ys.reverse.map (_ + ll(4))).toArray, 4)
  var res = 0 
  while (sc.hasNext) {
    val row = sc.nextLine
    println ("line: " + line) 
    res += affected (polygon, x, y, h, i, d, row.split (" "))     
  } 
  println (res)
}