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  1. //Devin Scheu                                  CS1A                                    Chapter 9, P. 538, #8
  2. //
  3. /**************************************************************
  4. *
  5. * DETERMINE MODE OF INTEGER ARRAY
  6. * ____________________________________________________________
  7. * This program finds the mode of a set of integer values
  8. * in an array, which is the value occurring most frequently.
  9. * ____________________________________________________________
  10. * INPUT
  11. * arraySize : The number of elements in the array
  12. * values : The array of integers
  13. *
  14. * OUTPUT
  15. * modeValue : The mode of the array or -1 if no mode exists
  16. *
  17. **************************************************************/
  18.  
  19. #include <iostream>
  20. #include <iomanip>
  21.  
  22. using namespace std;
  23.  
  24. // Function to find mode using pointer notation
  25. int findMode(int* arr, int size) {
  26.     if (size <= 0) return -1;
  27.  
  28.     int* count = new int[1000](); // Assume max value is 999, initialize to 0
  29.     int maxCount = 0;             // Track the highest frequency
  30.     int modeValue = -1;           // Track the mode value
  31.  
  32.     // Count frequency of each value and find the mode
  33.     for (int* ptr = arr; ptr < arr + size; ptr++) {
  34.         count[*ptr]++;
  35.         if (count[*ptr] > maxCount) {
  36.             maxCount = count[*ptr];
  37.             modeValue = *ptr; // Set mode to the first value with the new max count
  38.         }
  39.     }
  40.  
  41.     // Check if a mode exists (more than one occurrence)
  42.     if (maxCount <= 1) {
  43.         delete[] count;
  44.         return -1;
  45.     }
  46.  
  47.     // Count unique values with max count using a flag array
  48.     bool* seen = new bool[1000](); // Flag to mark seen values with max count
  49.     for (int i = 0; i < 1000; i++) seen[i] = false;
  50.     int uniqueMaxCount = 0;
  51.  
  52.     for (int* ptr = arr; ptr < arr + size; ptr++) {
  53.         if (count[*ptr] == maxCount && !seen[*ptr]) {
  54.             uniqueMaxCount++;
  55.             seen[*ptr] = true;
  56.             if (uniqueMaxCount > 1) {
  57.                 delete[] count;
  58.                 delete[] seen;
  59.                 return -1; // Multiple unique modes, no single mode
  60.             }
  61.         }
  62.     }
  63.  
  64.     delete[] count;
  65.     delete[] seen;
  66.     return modeValue;
  67. }
  68.  
  69. int main () {
  70.  
  71. 	//Variable Declarations
  72. 	int arraySize;                //INPUT      - The number of elements in the array
  73. 	int* values;                  //INPUT      - The array of integers
  74. 	int modeValue;                //OUTPUT     - The mode of the array or -1 if no mode exists
  75.  
  76. 	//Prompt for Input
  77. 	cout << "Enter the number of elements: ";
  78. 	cin >> arraySize;
  79. 	cout << arraySize << endl;
  80.  
  81. 	//Allocate dynamic array
  82. 	values = new int[arraySize];
  83.  
  84. 	//Input Values
  85. 	for (int i = 0; i < arraySize; i++) {
  86. 		cout << "Enter value " << (i + 1) << ": ";
  87. 		cin >> *(values + i);
  88. 		while (*(values + i) < 0) {
  89. 			cout << "\nError: Please enter a non-negative value: ";
  90. 			cin >> *(values + i);
  91. 		}
  92. 		cout << *(values + i) << endl;
  93. 	}
  94.  
  95. 	//Calculate Mode
  96. 	modeValue = findMode(values, arraySize);
  97.  
  98. 	//Separator and Output Section
  99. 	cout << "-------------------------------------------------------" << endl;
  100. 	cout << "OUTPUT:" << endl;
  101.  
  102. 	//Output Result
  103. 	if (modeValue == -1) {
  104. 		cout << left << setw(25) << "Mode:" << right << setw(15) << "No mode (-1)" << endl;
  105. 	} else {
  106. 		cout << left << setw(25) << "Mode:" << right << setw(15) << modeValue << endl;
  107. 	}
  108.  
  109. 	//Clean up memory
  110. 	delete[] values;
  111.  
  112. } //end of main()
Success #stdin #stdout 0.01s 5308KB
comments (?)
stdin 
6
1
2
2
4
4
4
stdout 
Enter the number of elements: 6
Enter value 1: 1
Enter value 2: 2
Enter value 3: 2
Enter value 4: 4
Enter value 5: 4
Enter value 6: 4
-------------------------------------------------------
OUTPUT:
Mode:                                  4
https://ideone.com/v85dOw
language:
C++ (gcc 8.3)
created:
9 days ago
visibility:
public

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