[Array] Sort the People - Easy

To sort people by their heights and names, we need a good sorting method. This method must look at both height and name. We have an array of people’s heights and names. The main goal is to sort by height from tallest to shortest. If two people are the same height, we will sort their names in alphabetical order.

In this article, we will look at many parts of the problem called “[Array] Sort the People - Easy.” We will first understand the problem. Then, we will find the best solutions using different programming languages like Java, Python, and C++. After that, we will check the time and space complexity of our solutions. We will also talk about edge cases, share good coding practices, and answer some common questions.

[Array] Sort the People Based on Height and Name
Understanding the Problem Statement for [Array] Sort the People - Easy
Optimal Solution Using Sorting in Java for [Array] Sort the People - Easy
Using Custom Comparators in Python for [Array] Sort the People - Easy
Efficient Implementation with STL in C++ for [Array] Sort the People - Easy
Analyzing Time Complexity for [Array] Sort the People - Easy
Exploring Space Complexity for [Array] Sort the People - Easy
Testing Edge Cases in [Array] Sort the People - Easy
Best Practices for Coding [Array] Sort the People - Easy
Frequently Asked Questions

If you want to see related problems, you can look at articles like Array Two Sum - Easy or Array Best Time to Buy and Sell Stock - Easy. These articles give more ideas about how to work with arrays.

Understanding the Problem Statement for [Array] Sort the People - Easy

The problem of “[Array] Sort the People - Easy” needs us to sort an array that has information about people. This information includes their names and heights. Each person is shown as a pair. One part is their name (which is a string) and the other part is their height (which is an integer). Our job is to sort this array by height in descending order. If two people have the same height, we need to sort them by their names in alphabetical order.

Input and Output

Input:
- An array of strings for people’s names.
- An array of integers for their heights.
Output:
- An array of strings that is sorted in the right order.

Example

Input:

names = ["Mary", "John", "Emma"]
heights = [180, 165, 170]

Output:

["Mary", "Emma", "John"]

Constraints

We can have from 1 to 100 people.
Each name has uppercase and lowercase letters. The length can be up to 100 characters.
Heights are positive whole numbers.

We can solve this problem using different sorting methods and data types. This question is popular in interviews to check our problem-solving and coding skills.

Optimal Solution Using Sorting in Java for [Array] Sort the People - Easy

To solve the problem of sorting people by their height and keeping the original order when heights are the same, we can use Java’s sorting tools. We will create a list of pairs. Each pair will have a person’s height and their name. Then we will sort this list.

Here is how we can do this in Java:

import java.util.*;

public class SortPeople {
    public static String[] sortPeople(String[] names, int[] heights) {
        int n = names.length;
        String[][] people = new String[n][2];

        // Create a 2D array of names and heights
        for (int i = 0; i < n; i++) {
            people[i][0] = names[i];
            people[i][1] = String.valueOf(heights[i]);
        }

        // Sort the array based on heights (descending)
        Arrays.sort(people, (a, b) -> Integer.compare(Integer.parseInt(b[1]), Integer.parseInt(a[1])));

        // Get the sorted names
        String[] sortedNames = new String[n];
        for (int i = 0; i < n; i++) {
            sortedNames[i] = people[i][0];
        }

        return sortedNames;
    }

    public static void main(String[] args) {
        String[] names = {"Alice", "Bob", "Charlie"};
        int[] heights = {165, 180, 175};

        String[] sortedNames = sortPeople(names, heights);
        System.out.println(Arrays.toString(sortedNames));
    }
}

Explanation:

We create a 2D array called people. Each part has a name and its height.
We use Arrays.sort with a special rule that sorts the array by height in descending order.
Then, we get the sorted names into a new array and return it.

This way, we sort the people by their heights. We also make sure that names stay in the right order when heights are the same. The time it takes to sort is O(n log n) because of the sorting step. This makes our method good for this problem.

If you want to learn more about sorting arrays, you can read the article on Array - Sort Array by Parity.

Using Custom Comparators in Python for [Array] Sort the People - Easy

To sort people by height and name in Python, we can use custom comparators. We want to sort the people first by height in descending order. If two people have the same height, we sort them by name in alphabetical order.

Here is how we can do this with the sorted() function and a custom key:

def sort_people(people):
    # Sort using a custom key
    return sorted(people, key=lambda person: (-person[1], person[0]))

# Example usage
people = [["Alice", 165], ["Bob", 180], ["Charlie", 165]]
sorted_people = sort_people(people)
print(sorted_people)  # Output: [['Bob', 180], ['Alice', 165], ['Charlie', 165]]

Explanation:

Lambda Function: The lambda function lambda person: (-person[1], person[0]) sorts the list of people. The negative sign in front of person[1] makes sure that we sort heights in descending order.
Tuple Comparison: Python sorts tuples in order. So if two people have the same height, it sorts them by name in ascending order.

Additional Considerations:

We need to make sure that the input is correct. It should be a list of lists. Each inner list must have a name and a height.
This way is simple and uses Python’s built-in sorting which is usually fast with a time complexity of O(n log n).

This method is easy to use for the “[Array] Sort the People - Easy” problem with custom comparators in Python. For more about array tasks, you can look at Array Two Sum - Easy.

Efficient Implementation with STL in C++ for [Array] Sort the People - Easy

We can make a solution for sorting people by height and name in C++ using the Standard Template Library (STL). The main idea is to make a vector of pairs. Each pair will have a height and the matching name. Then we can use the sort function from STL. We will use a custom way to compare for sorting by height and name.

Implementation Steps:

Define the Data Structure: We use a vector of pairs to keep heights and names.
Sort the Vector: We use the sort function with a custom way to compare for the sorting.

C++ Code Example:

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;

vector<string> sortPeople(vector<string>& names, vector<int>& heights) {
    vector<pair<int, string>> people;
    
    // Create a vector of pairs
    for (int i = 0; i < names.size(); ++i) {
        people.emplace_back(heights[i], names[i]);
    }
    
    // Sort the vector based on height (descending) and name (ascending)
    sort(people.begin(), people.end(), [](const pair<int, string>& a, const pair<int, string>& b) {
        if (a.first == b.first) {
            return a.second < b.second; // Sort by name if heights are equal
        }
        return a.first > b.first; // Sort by height
    });
    
    vector<string> sortedNames;
    // Extract sorted names
    for (const auto& person : people) {
        sortedNames.push_back(person.second);
    }
    
    return sortedNames;
}

int main() {
    vector<string> names = {"Alice", "Bob", "Charlie"};
    vector<int> heights = {170, 180, 165};

    vector<string> sortedNames = sortPeople(names, heights);
    
    for (const string& name : sortedNames) {
        cout << name << " ";
    }
    return 0;
}

Explanation of the Code:

We first make a vector of pairs called people. Each pair has a height and the matching name.

We use the sort function to sort the vector. The custom way to compare sorts first by height in descending order. If the heights are the same, it sorts by name in ascending order.

In the end, we take the sorted names into a new vector and return it.

This way, we sort the people based on the set criteria. We use the power of STL in C++. For more reading about array tasks, you might find Array Two Sum - Easy helpful.

Analyzing Time Complexity for [Array] Sort the People - Easy

In the problem of sorting people by height and name, we look at how well the sorting algorithm works. The time complexity depends on the sorting method we use.

Time Complexity Breakdown

Sorting by Height and Name:
- When we use a built-in sort function like Timsort in Python (used by sorted()), the average and worst-case time complexity is (O(n n)).
- If we make our own sorting, using comparison-based sorting gives us the same time complexity of (O(n n)) for average and worst cases.
Input Size:
- Let (n) be the number of people. To sort them, we need to compare each person with others. This is why we have the logarithmic part.
Space Complexity Consideration:
- The space complexity is (O(n)) if we create a new list to store the sorted people.

Example in Java

Here is how we can sort in Java:

import java.util.*;

public class SortPeople {
    public static String[] sortPeople(String[] names, int[] heights) {
        int n = names.length;
        String[][] people = new String[n][2];
        
        for (int i = 0; i < n; i++) {
            people[i][0] = names[i];
            people[i][1] = String.valueOf(heights[i]);
        }

        Arrays.sort(people, (a, b) -> {
            if (Integer.parseInt(b[1]) != Integer.parseInt(a[1])) {
                return Integer.parseInt(b[1]) - Integer.parseInt(a[1]);
            } else {
                return a[0].compareTo(b[0]);
            }
        });
        
        for (int i = 0; i < n; i++) {
            names[i] = people[i][0];
        }
        return names;
    }
}

Summary of Time Complexity

Best Case: (O(n n))
Average Case: (O(n n))
Worst Case: (O(n n))

This shows that sorting takes the most time when we sort people by height and name. For more on array sorting and techniques, we can read articles like Array Two Sum - Easy or Array Best Time to Buy and Sell Stock - Easy.

Exploring Space Complexity for [Array] Sort the People - Easy

In the problem of sorting people by height and name, we need to look at the space we use in our solution. The space we need depends on how we sort the array of people.

Input Space:
- The input is an array of n people. Each person is a tuple of height and name. This needs O(n) space to keep the input data.
Auxiliary Space:
- Different sorting algorithms need different auxiliary space:
  - Quick Sort: Normally, it needs O(log n) space for the call stack because of recursion.
  - Merge Sort: This one needs O(n) space for the temporary array when we merge.
In-Place Sorting:
- If we use an in-place sorting algorithm like Heap Sort, we can cut down the auxiliary space to O(1). This is because it only needs a fixed amount of space no matter how big the input is.
Custom Objects:
- If we make objects for each person, we also need to think about the memory for those objects. Each object may take more space based on how many attributes it has.
Overall Complexity:
- The total space complexity for sorting the people is mainly O(n) because of the input size. The auxiliary space changes with the sorting method we pick.

This analysis helps us see the memory needs of different sorting methods. This is important for making performance better when we deal with large datasets.

Testing Edge Cases in [Array] Sort the People - Easy

When we solve the problem of sorting people by height and name, we must think about edge cases. These cases help us check if our solution works for all kinds of inputs. Here are some important edge cases to test:

Empty Input:
- Input: heights = [], names = []
- Expected Output: []
Single Element:
- Input: heights = [65], names = ["Alice"]
- Expected Output: [("Alice", 65)]
Identical Heights:
- Input: heights = [65, 65, 65], names = ["Alice", "Bob", "Charlie"]
- Expected Output: [("Alice", 65), ("Bob", 65), ("Charlie", 65)] (sorted by name)
Multiple Heights, Same Name:
- Input: heights = [70, 68, 70], names = ["Alice", "Alice", "Alice"]
- Expected Output: [("Alice", 68), ("Alice", 70), ("Alice", 70)] (sorted by height)
Mixed Heights and Names:
- Input: heights = [70, 60, 80], names = ["Charlie", "Alice", "Bob"]
- Expected Output: [("Alice", 60), ("Bob", 70), ("Charlie", 80)]
Reverse Order:
- Input: heights = [80, 70, 60], names = ["Charlie", "Bob", "Alice"]
- Expected Output: [("Alice", 60), ("Bob", 70), ("Charlie", 80)]
Large Input:
- Input: heights = [i for i in range(1000, 0, -1)], names = [f"Name{i}" for i in range(1000, 0, -1)]
- Expected Output: A sorted list of names with their heights.

We test these edge cases to make sure our sorting function works well in many situations. It also shows us any problems in our logic. Here is an example of how we can sort in Python:

def sort_people(heights, names):
    combined = sorted(zip(names, heights), key=lambda x: (x[1], x[0]))
    return combined

# Test cases
print(sort_people([], []))  # Test 1
print(sort_people([65], ["Alice"]))  # Test 2
print(sort_people([65, 65, 65], ["Alice", "Bob", "Charlie"]))  # Test 3
print(sort_people([70, 68, 70], ["Alice", "Alice", "Alice"]))  # Test 4
print(sort_people([70, 60, 80], ["Charlie", "Alice", "Bob"]))  # Test 5
print(sort_people([80, 70, 60], ["Charlie", "Bob", "Alice"]))  # Test 6

Testing these edge cases helps us make sure our solution is strong for sorting people by height and name. For more about array problems, we can look at Array: Two Sum - Easy.

Best Practices for Coding [Array] Sort the People - Easy

When we solve the problem “[Array] Sort the People - Easy”, it is important to follow good coding practices. This helps us make our code easier to read, maintain, and efficient. Here are some main points to think about:

Use Clear Variable Names: We should choose names that show what the variable does. For example, we can use people for the list of people and sortedPeople for the output.
Break Code into Functions: It is good to split our code into smaller functions. This makes it easier to read and reuse. For example, we can have one function to sort people by height and another one to format the result.
Add Comments: We must add comments to explain any tricky parts of the code. Also, we should document what each function does and what it takes as input and gives as output. This helps others understand our code better.
Choose Good Data Structures: We can use tuples or objects to store height and name pairs. This will make sorting and getting elements easier.
Use Built-in Sorting: It is better to use built-in sorting functions. They are already optimized for speed. For example, we can use Python’s sorted() or Java’s Arrays.sort().
Custom Sorting: If we need to sort by more than one thing, like height and name, we should create custom comparators. This gives us better control over how we sort.
Handle Edge Cases: We should always think about edge cases, like empty lists or lists with the same heights. We need to add checks to handle these situations well.
Write Tests: We should write unit tests for different cases. This includes normal cases and edge cases. This way, we can make sure our solution works well.

Example Code Snippets

Java Example:

import java.util.Arrays;
import java.util.Comparator;

public class SortPeople {
    public static String[] sortPeople(String[] names, int[] heights) {
        String[][] people = new String[names.length][2];
        for (int i = 0; i < names.length; i++) {
            people[i][0] = names[i];
            people[i][1] = String.valueOf(heights[i]);
        }
        
        Arrays.sort(people, new Comparator<String[]>() {
            public int compare(String[] a, String[] b) {
                return Integer.compare(Integer.parseInt(b[1]), Integer.parseInt(a[1])); // Sort by height
            }
        });
        
        String[] sortedNames = new String[names.length];
        for (int i = 0; i < names.length; i++) {
            sortedNames[i] = people[i][0];
        }
        return sortedNames;
    }
}

Python Example:

def sort_people(names, heights):
    people = list(zip(names, heights))
    people.sort(key=lambda x: (-x[1], x[0]))  # Sort by height descending, then by name
    return [name for name, height in people]

Think About Performance: We should check the time complexity of our sorting. The built-in sort usually works in O(n log n), which is good for this task.
Don’t Repeat Code: If we have similar sorting code in different places, we should move that code to a utility function.

If we follow these good practices when coding for “[Array] Sort the People - Easy”, we will have a quality, easy-to-maintain, and efficient code. For more information on array problems, we can look at articles like Array Two Sum - Easy and Array Contains Duplicate - Easy.

Frequently Asked Questions

What is the problem statement for the “Sort the People” challenge?

The “Sort the People” challenge asks us to sort an array of people by their heights and names. We need to sort them mainly by height from high to low. For people with the same height, we sort their names in alphabetical order. This problem helps us understand sorting better. It is a common topic in coding interviews and competitions.

How do we implement sorting in Java for the “Sort the People” problem?

To sort in Java for the “Sort the People” problem, we can use the Arrays.sort() method. We also need a custom comparator. This comparator first compares the heights from high to low. Then it compares the names in alphabetical order. This way is quick and uses Java’s built-in sorting tools. It is a good solution for sorting people by height and name.

What Python techniques can we use for custom sorting in the “Sort the People” problem?

In Python, we can use the sorted() function with a lambda function to create a custom sort for the “Sort the People” problem. We can set the heights as the main key in reverse order and names as the second key. This method is short and works well for our sorting needs in this challenge.

How can C++ STL improve the efficiency of sorting for the “Sort the People” problem?

With C++ Standard Template Library (STL), we can sort the “Sort the People” problem easily using the sort() function from the <algorithm> header. We give a custom comparator that sorts heights from high to low and names from low to high. This way, we get good performance. This method uses C++’s strong sorting algorithms and gives us a clean solution.

What are the common edge cases to consider in the “Sort the People” challenge?

When we solve the “Sort the People” challenge, we must think about edge cases. These include empty arrays, arrays with just one person, and cases where many people have the same height. Also, we should check different name formats like uppercase and lowercase. Testing these edge cases makes sure our solution works well for many types of inputs.

For more coding challenges and solutions, we can check articles like Array: Two Sum - Easy or Array: Maximum Subarray - Easy.