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Posted By

jaircazarin on 11/08/08


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c optimization


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Boolean Matrix

 / Published in: C#
 

Define a two-dimensional boolean array. Minimize the memory allocated. Write a function to set a value to an element of this array.

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  1. sing System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Text;
  5.  
  6. namespace BooleanMatrix {
  7.     class BooleanMatrix {
  8.         private const int BITSPERWORD = 32;
  9.         private const int SHIFT = 5;
  10.         private const int MASK = 0x1F;
  11.         private int width;
  12.         private int height;
  13.         private int length;
  14.         private int[] bitset;
  15.  
  16.         public BooleanMatrix(int width, int height)
  17.         {
  18.             this.width = width;
  19.             this.height = height;
  20.             this.length = width * height;
  21.             bitset = new int[1 + this.length / BITSPERWORD];
  22.         }
  23.  
  24.         public void Set(int x, int y) {
  25.             int index = getIndex(x, y);
  26.             bitset[index >> SHIFT] |= (1 << (index & MASK));
  27.         }
  28.  
  29.         public void Clear(int x, int y) {
  30.             int index = getIndex(x, y);
  31.             bitset[index >> SHIFT] &= ~(1 << (index & MASK));
  32.         }
  33.  
  34.         public int Test(int x, int y) {
  35.             int index = getIndex(x, y);
  36.             return bitset[index >> SHIFT] & (1 << (index & MASK));
  37.         }
  38.  
  39.         private int getIndex(int x, int y) {
  40.             return x * this.width + y;
  41.         }
  42.  
  43.         public int Height {
  44.             get { return height; }
  45.         }
  46.  
  47.         public int Width {
  48.             get { return width; }
  49.         }
  50.     }
  51. }

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