Group Anagrams Using Hash Map in DSA C - Build from Scratch

Group Anagrams Using Hash Map

📖 Scenario: You work in a word game company. You want to group words that are anagrams of each other to help players find word matches quickly.

🎯 Goal: Build a program that groups a list of words into sets where each set contains words that are anagrams of each other.

📋 What You'll Learn

Create an array of strings with exact words given

Create a helper function to sort characters in a string

Use a hash map (dictionary) to group words by their sorted character key

Print the groups of anagrams

💡 Why This Matters

🌍 Real World

Grouping anagrams helps in word games, search engines, and text analysis to find related words quickly.

💼 Career

Understanding hash maps and string manipulation is essential for software development, especially in data processing and algorithm design.

1

Create the list of words

Create an array of strings called words with these exact entries: "eat", "tea", "tan", "ate", "nat", "bat".

DSA C

# Create the array of words
// Your code here

Hint

Use char *words[] = {"eat", "tea", "tan", "ate", "nat", "bat"}; to create the array.

2

Create a function to sort characters in a string

Write a function called sortString that takes a char* string and sorts its characters in alphabetical order.

DSA C

#include 

char *words[] = {"eat", "tea", "tan", "ate", "nat", "bat"};
int wordsCount = 6;

// Write sortString function below
// Your code here

Hint

Use nested loops to compare and swap characters to sort the string.

3

Group words by sorted key using a hash map

Create a hash map using arrays to group words by their sorted character key. Use a 2D array groups to store groups and an array groupCounts to count words in each group. For each word, create a copy, sort it using sortString, then check if the sorted key exists in groups. If yes, add the word to that group; if no, create a new group.

DSA C

#include 
#include 

char *words[] = {"eat", "tea", "tan", "ate", "nat", "bat"};
int wordsCount = 6;

void sortString(char *str) {
    int len = strlen(str);
    for (int i = 0; i  str[j]) {
                char temp = str[i];
                str[i] = str[j];
                str[j] = temp;
            }
        }
    }
}

// Group words by sorted key below
// Your code here

Hint

Use arrays to simulate a hash map by storing sorted keys and their groups. Use strcpy to copy strings.

4

Print the groups of anagrams

Add code inside main to print each group of anagrams. For each group, print words separated by spaces on one line.

DSA C

#include 
#include 
#include 

char *words[] = {"eat", "tea", "tan", "ate", "nat", "bat"};
int wordsCount = 6;

void sortString(char *str) {
    int len = strlen(str);
    for (int i = 0; i  str[j]) {
                char temp = str[i];
                str[i] = str[j];
                str[j] = temp;
            }
        }
    }
}

char groups[6][6][10];
int groupCounts[6] = {0};
char keys[6][10];
int groupIndex = 0;

int findGroup(char *key) {
    for (int i = 0; i < groupIndex; i++) {
        if (strcmp(keys[i], key) == 0) {
            return i;
        }
    }
    return -1;
}

int main() {
    for (int i = 0; i < wordsCount; i++) {
        char temp[10];
        strcpy(temp, words[i]);
        sortString(temp);
        int idx = findGroup(temp);
        if (idx == -1) {
            strcpy(keys[groupIndex], temp);
            strcpy(groups[groupIndex][0], words[i]);
            groupCounts[groupIndex] = 1;
            groupIndex++;
        } else {
            strcpy(groups[idx][groupCounts[idx]], words[i]);
            groupCounts[idx]++;
        }
    }
    // Print groups below
    for (int i = 0; i < groupIndex; i++) {
        for (int j = 0; j < groupCounts[i]; j++) {
            printf("%s ", groups[i][j]);
        }
        printf("\n");
    }
    return 0;
}

Hint

Use nested loops to print each group of words separated by spaces, then print a new line after each group.