DZone Snippets: Kanishkkunal's Code Snippets

Algortihm Challenge 1: No division!

kanishkkunal (Kanishk Kunal) — Fri, 29 Jun 2007 09:58:58 GMT

// http://gurus.wordpress.com/2007/06/28/algortihm-challenge-1-no-division/



P[0] = 1;

for (int i = 1; i < N; i++)

{

	P[i]=P[i-1]*X[i-1];

}

Q[N-1] = 1;

for (int i = N-2; i >= 1; i--)

{

	Q[i]=Q[i+1]*X[i+1];

}



for (int i = 0; i < N; i++)

{

	M[i]=P[i]*Q[i];

}

Double Array Manipulations

kanishkkunal (Kanishk Kunal) — Thu, 26 Oct 2006 02:48:41 GMT

// Manipulations with double dimension arrays



//equate two arrays

private static boolean isEqual(char [][]arr1, char [][]arr2) {

		if(arr1.length!=arr2.length) return false;

		boolean res = true;

		for(int i=0; i			res = res & Arrays.equals(arr1[i], arr2[i]);

		}

		return res;

	}

	

//rotate clockwise 90 degrees

private static char [][]rotate90(char [][]arr) {

	char [][]ret = new char[arr.length][arr[0].length];

	for(int j=0; j		for(int i=0; i			ret[i][j] = arr[j][i];

		}

	}		

	//print(ret);

	return reflect(ret);

}

	

//reflect horizontally	

private static char [][]reflect(char [][]arr) {

	char [][]ret = new char[arr.length][arr[0].length];

	for(int i=0; i		for(int j=0; j			ret[i][j] = arr[i][arr[i].length-j-1];

		}

	}		

	//print(ret);

	return ret;

}



//prints for debugging	

private static void print(char [][]arr) {

	for(int i=0; i		System.out.println(Arrays.toString(arr[i]));

	}

	System.out.println();

}

graham scan

kanishkkunal (Kanishk Kunal) — Mon, 16 Oct 2006 00:52:36 GMT

// graham scan incomplete



import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Arrays;

import java.util.StringTokenizer;

import java.util.Stack;

/*

ID: kanishk1

LANG: JAVA

TASK: moat

*/



public class moat {

	static class Point implements Comparable {

		public int x; public int y;

		Point pv;

		public Point(int x, int y) {

			this.x = x;

			this.y = y;

		}

		public void setPivot(Point pv) {

			this.pv = pv;

		}

		public int compareTo(Object o) {

			Point p = (Point)o;

			double a1 = ((y-pv.y)*1.0)/(x-pv.x);

			if(a1<0) a1 = 2+a1;

			double a2 = ((p.y-pv.y)*1.0)/(p.x-pv.x);

			if(a2<0) a2 = 2+a2;

			if(a1>a2) return 1;

			else if(a1			else return y-p.y;

		}

	}

	static Point []points;

	 public static void main (String [] args) throws IOException {

		    

		 // Use BufferedReader rather than RandomAccessFile; it's much faster

		    BufferedReader f = new BufferedReader(new FileReader("moat.in"));

		                                                  // input file name goes above

		    PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("moat.out")));



		    int N = Integer.parseInt(f.readLine());

		    points = new Point[N];

		    int lx = Integer.MAX_VALUE, ly = Integer.MAX_VALUE;

		    Point p = null;

		    for(int i=0; i		    	StringTokenizer st = new StringTokenizer(f.readLine());

		    	int x = Integer.parseInt(st.nextToken());

		    	int y = Integer.parseInt(st.nextToken());

		    	

		    	points[i] = new Point(x,y);

		    	if(y		    		ly =y;

		    		lx = x;

		    		p = points[i];

		    	}

		    	else if(y==ly && x		    		lx = x;

		    		p = points[i];

		    	}

		    }

		    for(int i=0; i		    	points[i].setPivot(p);

		    }

		    Arrays.sort(points);

		    for(int i=0; i		    {

		    	System.out.println(points[i].x+" "+points[i].y);

		    }

		    Stack stack = new Stack();

		    stack.push(points[0]);

		    stack.push(points[1]);

		    for(int i=2; i		    	Point top = (Point)stack.pop();

		    	Point second = (Point)stack.pop();

		        int o = Cross_product(second, top, points[i]);

		        stack.push(second);

		        stack.push(top);

		        if(o == 0) {

		        	stack.pop();

		        	stack.push(points[i]);

		        }

		        else if (o > 0) {

		        	stack.push(points[i]);

		        }

		        else {

		                while (o <= 0 && stack.size() > 2) {

		                        stack.pop();

		                        top = (Point)stack.pop();

		        		    	second = (Point)stack.pop();

		                        o = Cross_product(second, top, points[i]);

		                        stack.push(second);

		        		        stack.push(top);

		                }

		                stack.push(points[i]);

		        }

		    }

		    System.out.println("Done");

			while(stack.size()>0) {

				Point pp = (Point)stack.pop();

				System.out.println(pp.x+" "+pp.y);

			}

		    //out.println(ans);                        

		    out.close();                                 

		    System.exit(0); 

	 }

	 

	 private static int Cross_product(Point p1, Point p2, Point p3) {

		 return (p2.x - p1.x)*(p3.y - p1.y) - (p3.x - p1.x)*(p2.y - p1.y);	

	 }

}

graph traversal

kanishkkunal (Kanishk Kunal) — Mon, 16 Oct 2006 00:50:52 GMT

// Graph traversal



import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.StringTokenizer;



/*

ID: kanishk1

LANG: JAVA

TASK: skate

*/



import java.util.*;

import java.io.*;



public class skate {

	 static char [][]arr;

	 static ArrayList list = new ArrayList();

	 static PrintWriter out;

	 public static void main (String [] args) throws IOException {

	    // Use BufferedReader rather than RandomAccessFile; it's much faster

	    BufferedReader f = new BufferedReader(new FileReader("skate.in"));

	                                                  // input file name goes above

	    out = new PrintWriter(new BufferedWriter(new FileWriter("skate.out")));

	    // Use StringTokenizer vs. readLine/split -- lots faster

	    StringTokenizer st = new StringTokenizer(f.readLine());

	    int R = Integer.parseInt(st.nextToken());   

	    int C = Integer.parseInt(st.nextToken());   

	    //System.out.println(R+" "+C);

	    arr = new char[R][C];

	    for(int i=0; i	    	arr[i] = f.readLine().trim().toCharArray();

	    }

	    list.add(pair(0,0));

	    doTask(0, 0);

	  }		  

	 

	 private static void doTask(int i, int j) {

		 //System.out.println(pair(i,j));

		 if(i==arr.length-1 && j==arr[0].length-1) {

			 //System.out.println("here"); 

			 out.println(printAnswer(list));                        

			 out.close();                                 

			 System.exit(0); 

		 }

		 if(isValid(i+1, j)) {

			 list.add(pair(i+1,j));

			 arr[i+1][j] = '@';

			 doTask(i+1,j);

			 arr[i+1][j] = '.';

			 list.remove(pair(i+1,j));

		 }

		 if(isValid(i-1, j)) {

			 list.add(pair(i-1,j));

			 arr[i-1][j] = '@';

			 doTask(i-1,j);

			 arr[i-1][j] = '.';

			 list.remove(pair(i-1,j));

		 }

		 if(isValid(i, j+1)) {

			 arr[i][j+1] = '@';

			 list.add(pair(i,j+1));

			 doTask(i,j+1);

			 arr[i][j+1] = '.';

			 list.remove(pair(i,j+1));

		 }

		 if(isValid(i, j-1)) {

			 arr[i][j-1] = '@';

			 list.add(pair(i,j-1));

			 doTask(i,j-1);

			 arr[i][j-1] = '.';

			 list.remove(pair(i,j-1));

		 }

		 return;

	 }

	 

	 private static boolean isValid(int i, int j) {

		 if(i<0 || j<0 || i>=arr.length || j>=arr[0].length) return false;

		 if(arr[i][j]!='.') return false;

		 return true;

	 }

	 

	 private static String pair(int i, int j) {

		 return (i+1)+" "+(j+1);

	 }

	 

	 private static String printAnswer(ArrayList list) {

		 String ans = "";

		 for(int i=0; i			 ans+=list.get(i);

			 if(i!=list.size()-1) ans+="\n";

		 }

		 return ans;

	 }

}

PHP GET and POST Variables

kanishkkunal (Kanishk Kunal) — Fri, 22 Sep 2006 07:04:02 GMT

// The following code will easily retrieve all of the GET and POST data for you and load it into appropriately named PHP variables. The same code will also work to get parameters added to the end of URLs via other methods other than using GET with a form.



$q = explode("&",$_SERVER["QUERY_STRING"]);

foreach ($q as $qi)

{

  if ($qi != "")

  {

    $qa = explode("=",$qi);

    list ($key, $val) = $qa;

    if ($val)

      $$key = urldecode($val);

  }

}

 

reset ($_POST);

while (list ($key, $val) = each ($_POST))

{

  if ($val)

    $$key = $val;

}

isPrime

kanishkkunal (Kanishk Kunal) — Sun, 10 Sep 2006 05:06:01 GMT

// finding whether 'n' is prime or not



private boolean isPrime (int n)

{

   if (n<=1) return false;

   if (n==2) return true;

   if (n%2==0) return false;

   int m=(int)Math.round(Math.sqrt(n));



   for (int i=3; i<=m; i+=2)

      if (n%i==0)

         return false;



   return true;

}

GCD of two numbers.

kanishkkunal (Kanishk Kunal) — Sun, 10 Sep 2006 03:28:02 GMT

// finds GCD of a and b using Euclidian algorithm



public int GCD(int a, int b)

{

   if (b==0) return a;

   return GCD(b,a%b);

}