Question

Submit Chapter7.java with four (4) public static methods as follows:

A. Write a method called mostCommon that accepts an array of integers as its only parameter, and returns the int that occurs most frequently. Break ties by returning the lower value For example, {1,2,2,3,4,4} would return 2 as the most common int.

B. Write mostCommon (same as above) that accepts an array of doubles, and returns the double that occurs most frequently. Consider any double values that are within 0.1% of each other to be equal. So 2.34 and 2.35 are not equal, but 22222.34 and 22222.35 ARE considered equal.

C. Write a method called vowelCount that accepts a String as its only parameter, and returns an array int[5] containing the count of vowels a,e,i,o,u in that String, using ignoreCase. For example, vowelCount("") returns {0,0,0,0,0}, and for the call vowelCount("Bill Iverson") your method returns {0,1,2,1,0} because there is one 'e' and two 'i' vowels (ignore case) and one 'o' with zero counts for 'a' and 'u' vowels.

D. Write a method called isSquare that accepts a two-dimensional array of integers as a parameter and returns true if the number of columns in every row equals the number of rows in every column. For example, isSquare for {[2,7,6], [9,5,1], [4,3,8]} returns true because there are 3 columns and 3 rows. But isSquare {[2,7], [9,5], [4,3]} will return false. Your method must work for any dimension.

Answer 1

Problem#A:

public static int mostCommon(int []array)
    {HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
    int max=1,temp;
    for(int i=0;i<array.length;i++)
        {
            if(hm.get(array[i])!=null)
            {int count=hm.get(array[i]);
            count=count+1;
            hm.put(array[i],count);
            if(count>max)
                {max=count;
                 temp=array[i];}
            }
            else
            {hm.put(array[i],1);}
        }
        return temp;
    }

Problem#B:

static int countOccurrences(double[] list, double targetValue) {
    int count = 0;
    for (int i = 0; i < list.length; i++) {
        if (list[i] == targetValue)
            count++;
    }
}


static double mostCommon(double[] list) {
    int mostFrequentCount = 0;
    double mostFrequentValue = 0;
    for (int i = 0; i < list.length; i++) {
        double value = list[i];
        int count = countOccurrences(list, value);
        if (count > mostFrequentCount) {
            mostFrequentCount = count;
            mostFrequentValue = value;
        }
    }
    return mostFrequentValue;
}

Problem#C:

public static int VowelCount(String word) {
int count[5],i;
for (i=0;i<5;i++)
    count[i]=0;
if (word != null) {
    word = word.trim().toLowerCase();
}
if (word == null || word.length() < 1) {
    return count;
}
for (int index = 0; index < word.length(); index++) {
  
    char fred = word.charAt(index);
    if (fred == 'a')
      ++count[0];
    if (fred == 'e')
      ++count[1];
    if (fred == 'i')
      ++count[2];
    if (fred == 'o')
      ++count[3];
    if (fred == 'u')
      ++count[4];
}
System.out.println("For the word \"" + word
      + "\" there are {");
   for (i=0;i<5;i++)
       System.out.println(count[i] + ", ");
    System.out.println("} vowels");
}

Problem#D:

public boolean isSquare(int[][] dd) {
    int r = dd.length;
    int sum = 0;
    for (int i=0; i<r ; i++) {
   sum += dd[0][i];
   if (dd[i].length != r) {
        return false;
   }
    }

    int sum2 = 0;
    // column sum
    for (int i=0; i<r;i++) {
   for (int j=0; j<r; j++) {
        sum2 += dd[i][j];
   }
   if (sum2 != sum)
        return false;
   sum2 = 0;
    }
    // row sum
    for (int j=0; j<r; j++) {
   for (int i=0; i<r; i++) {      
        sum2 += dd[i][j];
   }
   if (sum2 != sum)
        return false;
   sum2 = 0;
    }
    // diagram
    int sum3 = 0;
    for (int i=0; i<r; i++) {
   sum2 += dd[i][i];
   sum3 += dd[i][r-i-1];
    }
    if (sum2 != sum)
   return false;
    if (sum3 != sum)
   return false;
  
    return true;
}