How to find the Item with Maximum Number of Occurrences in a Vector in C++ - Step by Step Examples

How to find the Item with Maximum Number of Occurrences in a Vector in C++ ?

Answer

To find the item with the maximum number of occurrences in a Vector in C++, you can use an unordered_map to count the occurrences of each item and then find the item with the maximum count.


✐ Examples

1 Find Item with Maximum Occurrences in a Vector of Strings

In this example,

  1. We start by including the necessary headers: #include <iostream>, #include <vector>, and #include <unordered_map> for using input-output streams, vectors, and unordered maps respectively.
  2. We create a vector named vec containing several string elements.
  3. We create an unordered_map named counts to store the occurrences of each string in the vector. The keys of the unordered_map will be the strings, and the values will be their counts.
  4. We use a for loop to iterate through each element in the vector. For each element, we increment its count in the unordered_map.
  5. We initialize two variables, max_item and max_count, to keep track of the item with the maximum occurrences and its count. max_item is initialized as an empty string, and max_count is initialized to 0.
  6. We iterate through the unordered_map to find the item with the highest count. If we find an item with a count higher than max_count, we update max_item and max_count.
  7. Finally, we print the item with the maximum number of occurrences to standard output using std::cout.

C++ Program

#include <iostream>
#include <vector>
#include <unordered_map>

int main() {
    // Step 2: Create a vector of strings
    std::vector<std::string> vec = {"apple", "banana", "apple", "orange", "banana", "apple"};
    
    // Step 3: Create an unordered_map to count occurrences
    std::unordered_map<std::string, int> counts;
    
    // Step 4: Count occurrences of each item in the vector
    for (const auto& item : vec) {
        counts[item]++;
    }
    
    // Step 5: Initialize variables to find the item with the maximum occurrences
    std::string max_item;
    int max_count = 0;
    
    // Step 6: Iterate through the unordered_map to find the item with the highest count
    for (const auto& pair : counts) {
        if (pair.second > max_count) {
            max_item = pair.first;
            max_count = pair.second;
        }
    }
    
    // Step 7: Print the item with the maximum occurrences
    std::cout << "Item with maximum occurrences: " << max_item << std::endl;
    
    return 0;
}

Output

Item with maximum occurrences: apple

2 Find Item with Maximum Occurrences in a Vector of Integers

In this example,

  1. We start by including the necessary headers: #include <iostream>, #include <vector>, and #include <unordered_map> for using input-output streams, vectors, and unordered maps respectively.
  2. We create a vector named vec containing several integer elements.
  3. We create an unordered_map named counts to store the occurrences of each integer in the vector. The keys of the unordered_map will be the integers, and the values will be their counts.
  4. We use a for loop to iterate through each element in the vector. For each element, we increment its count in the unordered_map.
  5. We initialize two variables, max_item and max_count, to keep track of the item with the maximum occurrences and its count. max_item is initialized as 0, and max_count is initialized to 0.
  6. We iterate through the unordered_map to find the item with the highest count. If we find an item with a count higher than max_count, we update max_item and max_count.
  7. Finally, we print the item with the maximum number of occurrences to standard output using std::cout.

C++ Program

#include <iostream>
#include <vector>
#include <unordered_map>

int main() {
    // Step 2: Create a vector of integers
    std::vector<int> vec = {1, 2, 3, 1, 2, 1, 4, 1, 5, 1};
    
    // Step 3: Create an unordered_map to count occurrences
    std::unordered_map<int, int> counts;
    
    // Step 4: Count occurrences of each item in the vector
    for (const auto& item : vec) {
        counts[item]++;
    }
    
    // Step 5: Initialize variables to find the item with the maximum occurrences
    int max_item = 0;
    int max_count = 0;
    
    // Step 6: Iterate through the unordered_map to find the item with the highest count
    for (const auto& pair : counts) {
        if (pair.second > max_count) {
            max_item = pair.first;
            max_count = pair.second;
        }
    }
    
    // Step 7: Print the item with the maximum occurrences
    std::cout << "Item with maximum occurrences: " << max_item << std::endl;
    
    return 0;
}

Output

Item with maximum occurrences: 1

Summary

In this tutorial, we learned How to find the Item with Maximum Number of Occurrences in a Vector in C++ language with well detailed examples.


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