Data_Structures_And_Algorithms_In_Java_Robert_Lafore_2nd_Edition_Programming

package chapter2;
// 2.1 To the HighArray class in the highArray.java program (Listing 2.3), add a
// method called getMax() that returns the value of the highest key in the array,
// or –1 if the array is empty. Add some code in main() to exercise this method.
// You can assume all the keys are positive numbers.

// highArray.java
// demonstrates array class with high-level interface
// to run this program: C>java HighArrayApp
////////////////////////////////////////////////////////////////
class HighArray
   {
   private long[] a;                 // ref to array a
   private int nElems;               // number of data items
   //-----------------------------------------------------------
   public HighArray(int max)         // constructor
      {
      a = new long[max];                 // create the array
      nElems = 0;                        // no items yet
      }
   //-----------------------------------------------------------
   public boolean find(long searchKey)
      {                              // find specified value
      int j;
      for(j=0; j<nElems; j++)            // for each element,
         if(a[j] == searchKey)           // found item?
            break;                       // exit loop before end
      if(j == nElems)                    // gone to end?
         return false;                   // yes, can't find it
      else
         return true;                    // no, found it
      }  // end find()
   //-----------------------------------------------------------
   public void insert(long value)    // put element into array
      {
      a[nElems] = value;             // insert it
      nElems++;                      // increment size
      }
   //-----------------------------------------------------------
   public boolean delete(long value)
      {
      int j;
      for(j=0; j<nElems; j++)        // look for it
         if( value == a[j] )
            break;
      if(j==nElems)                  // can't find it
         return false;
      else                           // found it
         {
         for(int k=j; k<nElems; k++) // move higher ones down
            a[k] = a[k+1];
         nElems--;                   // decrement size
         return true;
         }
      }  // end delete()
   //-----------------------------------------------------------
   public void display()             // displays array contents
      {
      for(int j=0; j<nElems; j++)       // for each element,
         System.out.print(a[j] + " ");  // display it
      System.out.println("");
      }
   //-----------------------------------------------------------
   
   // start here
   public long getMax() {
	   if(nElems == 0) {
		   return -1;   //数组为空
	   }
	   
	   long max = a[0];
	   for(int j = 1; j < nElems; j++) {
		   if(max < a[j]) {
			   max = a[j];
		   }
	   }
	   return max;
   }
   // end here
   
   }  // end class HighArray
////////////////////////////////////////////////////////////////
class HighArrayApp
   {
   public static void main(String[] args)
      {
      int maxSize = 100;            // array size
      HighArray arr;                // reference to array
      arr = new HighArray(maxSize); // create the array

      arr.insert(77);               // insert 10 items
      arr.insert(99);
      arr.insert(44);
      arr.insert(55);
      arr.insert(22);
      arr.insert(88);
      arr.insert(11);
      arr.insert(00);
      arr.insert(66);
      arr.insert(33);

      arr.display();                // display items

      int searchKey = 35;           // search for item
      if( arr.find(searchKey) )
         System.out.println("Found " + searchKey);
      else
         System.out.println("Can't find " + searchKey);

      arr.delete(00);               // delete 3 items
      arr.delete(55);
      arr.delete(99);

      arr.display();                // display items again
      
      // start here
      System.out.println(arr.getMax());
      // end here
      }  // end main()
   }  // end class HighArrayApp

77 99 44 55 22 88 11 0 66 33 
Can't find 35
77 44 22 88 11 66 33 
88

package chapter2;
// Modify the method in Programming Project 2.1 so that the item with the
// highest key is not only returned by the method, but also removed from the
// array. Call the method removeMax().

// highArray.java
// demonstrates array class with high-level interface
// to run this program: C>java HighArrayApp
////////////////////////////////////////////////////////////////
class HighArray
   {
   private long[] a;                 // ref to array a
   private int nElems;               // number of data items
   //-----------------------------------------------------------
   public HighArray(int max)         // constructor
      {
      a = new long[max];                 // create the array
      nElems = 0;                        // no items yet
      }
   //-----------------------------------------------------------
   public boolean find(long searchKey)
      {                              // find specified value
      int j;
      for(j=0; j<nElems; j++)            // for each element,
         if(a[j] == searchKey)           // found item?
            break;                       // exit loop before end
      if(j == nElems)                    // gone to end?
         return false;                   // yes, can't find it
      else
         return true;                    // no, found it
      }  // end find()
   //-----------------------------------------------------------
   public void insert(long value)    // put element into array
      {
      a[nElems] = value;             // insert it
      nElems++;                      // increment size
      }
   //-----------------------------------------------------------
   public boolean delete(long value)
      {
      int j;
      for(j=0; j<nElems; j++)        // look for it
         if( value == a[j] )
            break;
      if(j==nElems)                  // can't find it
         return false;
      else                           // found it
         {
         for(int k=j; k<nElems; k++) // move higher ones down
            a[k] = a[k+1];
         nElems--;                   // decrement size
         return true;
         }
      }  // end delete()
   //-----------------------------------------------------------
   public void display()             // displays array contents
      {
      for(int j=0; j<nElems; j++)       // for each element,
         System.out.print(a[j] + " ");  // display it
      System.out.println("");
      }
   //-----------------------------------------------------------
   
   // start here
   public long getMax() {
	   if(nElems == 0) {
		   return -1;   //数组为空
	   }
	   
	   long max = a[0];
	   for(int j = 1; j < nElems; j++) {
		   if(max < a[j]) {
			   max = a[j];
		   }
	   }
	   return max;
   }
   
   public boolean removeMax() {
	   if(getMax() == -1) {
		   return false;
	   }
	   
	   return delete(getMax());
   }
   // end here
   
   }  // end class HighArray
////////////////////////////////////////////////////////////////
class HighArrayApp
   {
   public static void main(String[] args)
      {
      int maxSize = 100;            // array size
      HighArray arr;                // reference to array
      arr = new HighArray(maxSize); // create the array

      arr.insert(77);               // insert 10 items
      arr.insert(99);
      arr.insert(44);
      arr.insert(55);
      arr.insert(22);
      arr.insert(88);
      arr.insert(11);
      arr.insert(00);
      arr.insert(66);
      arr.insert(33);

      arr.display();                // display items

      int searchKey = 35;           // search for item
      if( arr.find(searchKey) )
         System.out.println("Found " + searchKey);
      else
         System.out.println("Can't find " + searchKey);

      arr.delete(00);               // delete 3 items
      arr.delete(55);
      arr.delete(99);

      arr.display();                // display items again
      
      // start here
      System.out.println(arr.getMax());
      arr.removeMax();
      System.out.println(arr.getMax());
      // end here
      }  // end main()
   }  // end class HighArrayApp

77 99 44 55 22 88 11 0 66 33 
Can't find 35
77 44 22 88 11 66 33 
88
77