anil477

class Solution {
    
    
       // 93. Restore IP Addresses
        // https://leetcode.com/problems/restore-ip-addresses/
      public List<String> restoreIpAddresses(String rawIpString) {
        List<String> restoredIps = new ArrayList<>();
        restoreIps(0, 0, new int[4], rawIpString, restoredIps);

        return restoredIps;

anil477

public class Solution {
    
    // 79. Word Search
    // https://leetcode.com/problems/word-search/
    
    public boolean exist(char[][] board, String word) {
        for(int i = 0; i < board.length; i++)
            for(int j = 0; j < board[0].length; j++){
               if (board[i][j] == word.charAt(0)) {
                    if(exist(board, i, j, word, 0))

anil477

public class Solution {
    // 37. Sudoku Solver
    // https://leetcode.com/problems/sudoku-solver/
    public void solveSudoku(char[][] board) {
        if(board == null || board.length == 0)
            return;
        solve(board);
    }
    
    public boolean solve(char[][] board){

anil477

class Solution {
    
    // 22. Generate Parentheses
    // https://leetcode.com/problems/generate-parentheses/
    
    public List<String> generateParenthesis(int n) {
        List<String> ans = new ArrayList();
        backtrack(ans, new StringBuilder(), 0, 0, n);
        return ans;
    }

anil477

class Solution {
    
    // 17. Letter Combinations of a Phone Number
    // https://leetcode.com/problems/letter-combinations-of-a-phone-number/
    // https://leetcode.com/problems/letter-combinations-of-a-phone-number/discuss/8109/My-recursive-solution-using-Java/222635
    
    private static final String[] KEYS = { "", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz" };
    
    public List<String> letterCombinations(String digits) {
    		List<String> ret = new LinkedList<String>();

anil477

class Solution {
    
    
    // https://leetcode.com/problems/combination-sum-ii/
    // 40. Combination Sum II

    public List<List<Integer>> combinationSum2(int[] candidates, int target) {
        List<List<Integer>> list = new ArrayList<>();
        Arrays.sort(candidates);
        boolean[] used = new boolean[candidates.length];

anil477

class Solution {
    
    // 39. Combination Sum
    // https://leetcode.com/problems/combination-sum/

    public List<List<Integer>> combinationSum(int[] nums, int target) {
        List<List<Integer>> list = new ArrayList<>();
        Arrays.sort(nums);
        backtrack(list, new ArrayList<>(), nums, target, 0);
        return list;

anil477

class Solution {
    
    // https://leetcode.com/problems/subsets-ii/
    // 90. Subsets II

    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> output = new LinkedList();
        boolean[] used = new boolean[nums.length];
        Arrays.sort(nums);
        rec(nums, output, new ArrayList<>(), 0, used);

anil477

class Solution {

    // 78. Subsets
    // https://leetcode.com/problems/subsets/
    
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> output = new LinkedList();
        rec(nums, output, new ArrayList<>(), 0);
        // Arrays.sort(nums);
        return output;

anil477

public class Solution {
    
    // https://leetcode.com/problems/permutations-ii/
    // 47. Permutations II
    // https://leetcode.com/problems/permutations/discuss/18239/A-general-approach-to-backtracking-questions-in-Java-(Subsets-Permutations-Combination-Sum-Palindrome-Partioning)
    public List<List<Integer>> permuteUnique(int[] nums) {
        List<List<Integer>> res = new ArrayList<List<Integer>>();
        if(nums==null || nums.length==0) return res;
        boolean[] used = new boolean[nums.length];
        List<Integer> list = new ArrayList<Integer>();