solved leetcode sudoko problem using Hashmap

deepi907 — Wed, 28 Aug 2024 09:43:58 +0000

class Solution {
1. public void solveSudoku(char[][] board) {
2. HashMap> rows = new HashMap<>();
3. HashMap> cols = new HashMap<>();
4. HashMap> boxes = new HashMap<>();

Here three hashmap used that is row,cols,and boxes Now
it will efficiently keep track of which numbers are already used in each row, column, and 3x3 sub-box of the Sudoku board.

Each entry in these hashmaps is a HashSet to store characters representing numbers.

// Initialize hashmaps
for (int i = 0; i < 9; i++) {
rows.put(i, new HashSet<>());
cols.put(i, new HashSet<>());
boxes.put(i, new HashSet<>());
}
// Fill the hashmaps with the existing numbers on the board
for (int r = 0; r < 9; r++) {
for (int c = 0; c < 9; c++) {
char num = board[r][c];
if (num != '.') {
rows.get(r).add(num);
cols.get(c).add(num);
int boxIndex = (r / 3) * 3 + c / 3;
boxes.get(boxIndex).add(num);
}
}
}
// Start solving the puzzle using backtracking
solve(board, rows, cols, boxes, 0, 0);
}
private boolean solve(char[][] board, HashMap> rows, HashMap> cols, HashMap> boxes, int r, int c) {
if (r == 9) return true; // Puzzle solved
if (c == 9) return solve(board, rows, cols, boxes, r + 1, 0);
if (board[r][c] != '.') return solve(board, rows, cols, boxes, r, c + 1);
int boxIndex = (r / 3) * 3 + c / 3;
// Try placing numbers from 1 to 9
for (char num = '1'; num <= '9'; num++) {
if (!rows.get(r).contains(num) && !cols.get(c).contains(num) && !boxes.get(boxIndex).contains(num)) {
// Place the number
board[r][c] = num;
rows.get(r).add(num);
cols.get(c).add(num);
boxes.get(boxIndex).add(num);
// Continue solving with the next empty cell
if (solve(board, rows, cols, boxes, r, c + 1)) return true;
// Backtrack
board[r][c] = '.';
rows.get(r).remove(num);
cols.get(c).remove(num);
boxes.get(boxIndex).remove(num);
}
}
return false; // No valid solution found, backtrack
}
} When backtracking, removing a number from the hashmaps is straightforward and ensures that all constraints are maintained.

wordle

deepi907 — Wed, 10 Jul 2024 13:48:45 +0000

i took this challenge as frontend developer.Wordle is a daily word guessing game. Players guess a secret 5-letter word, receiving feedback on correct letters and positions. Implemented with HTML/CSS for interface and JavaScript for logic, it fetches words from an API, validates guesses, and tracks remaining attempts for a complete gaming experience."

DEV Community: deepi907

solved leetcode sudoko problem using Hashmap

wordle