Word Search in Grid Using Backtracking in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the current cell matches the current character of the word.

DSA C

if (board[row][col] == [1]) {
    // proceed with backtracking
}

Drag options to blanks, or click blank then click option'

A'*'

Bword[0]

C'\0'

Dword[index]

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with word[0] always checks only the first character.

Using '*' or '\0' does not check the correct character.

We compare the board cell with the current character of the word at position index.

2fill in blank

medium

Complete the code to mark the current cell as visited by replacing it with a special character.

DSA C

char temp = board[row][col];
board[row][col] = [1];

// backtracking calls

board[row][col] = temp;

Drag options to blanks, or click blank then click option'

A'*'

B'#'

C'\0'

D' '

Attempts:

3 left

💡 Hint

Common Mistakes

Using '\0' can cause string termination issues.

Using ' ' (space) might be confusing if spaces are in the grid.

We mark the cell as visited by replacing it with '*', a character not in the word.

3fill in blank

hard

Fix the error in the recursive call to explore the next character in the word.

DSA C

if (backtrack(board, word, row + 1, col, [1], rows, cols) ||
    backtrack(board, word, row - 1, col, [1], rows, cols) ||
    backtrack(board, word, row, col + 1, [1], rows, cols) ||
    backtrack(board, word, row, col - 1, [1], rows, cols)) {
    return 1;
}

Drag options to blanks, or click blank then click option'

Aindex - 1

Bindex

Cindex + 1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using index without increment causes infinite loops.

Decrementing index goes backward in the word.

We move to the next character in the word by increasing index by 1.

4fill in blank

hard

Fill both blanks to check if the current position is out of bounds or the cell is already visited.

DSA C

if (row [1] 0 || row [2] rows || col < 0 || col >= cols || board[row][col] == '*') {
    return 0;
}

Drag options to blanks, or click blank then click option'

A<

B>=

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' for lower bound allows -1 which is invalid.

Using '>' for upper bound misses the last valid index.

We check if row is less than 0 or greater or equal to rows to stay inside the grid.

5fill in blank

hard

Fill all three blanks to complete the main function that starts the search for the word in the grid.

DSA C

int exist(char** board, int boardSize, int* boardColSize, char* word) {
    for (int i = 0; i < boardSize; i++) {
        for (int j = 0; j < [1]; j++) {
            if (backtrack(board, word, i, j, 0, boardSize, [2])) {
                return [3];
            }
        }
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

A*boardColSize

BboardColSize[0]

C1

DboardSize

Attempts:

3 left

💡 Hint

Common Mistakes

Using boardSize for columns is incorrect.

Returning 0 inside the loop misses found words.

We use boardColSize[0] to get the number of columns, and return 1 if word is found.