BiruLyu

class Solution {
    int count = 0;
    int N = 0;
    public boolean canVisitAllRooms(List<List<Integer>> rooms) {
        if (rooms == null || rooms.size() < 1) return true;
        int n = rooms.size();
        count = n;
        N = n;
        boolean[] visited = new boolean[n];
        Set<Integer> canReach = new HashSet<>();

BiruLyu

class Solution {
    public List<Integer> splitIntoFibonacci(String S) {
        List<Integer> res = new ArrayList<>();
        int len = S.length();
        for (int i = 1; i < len && i < 11; i++) {
            if (S.charAt(0) == '0' && i > 1) return res;
            for (int j = 1; j < len - i && j < 11; j++) {
                if (S.charAt(i) == '0' && j > 1) continue;
                long a = Long.valueOf(S.substring(0, i));
                long b = Long.valueOf(S.substring(i, i + j));

BiruLyu

class Solution {
    public int numMagicSquaresInside(int[][] grid) {
        if (grid == null || grid.length < 3 || grid[0].length < 3) return 0;
        
        int m = grid.length, n = grid[0].length;
        boolean[] visited = new boolean[9];
        int[] rows = new int[3];
        int[] cols = new int[3];
        int[] diags = new int[2];
        boolean flag = false;

BiruLyu

/**
 * // This is the Master's API interface.
 * // You should not implement it, or speculate about its implementation
 * interface Master {
 *     public int guess(String word) {}
 * }
 */
class Solution {
    private int match(String guess, String w) {
        int match = 0;

BiruLyu

class Solution {
    public int[][] flipAndInvertImage(int[][] A) {
        if (A == null || A.length < 1 || A[0].length < 1) return A;
        int m = A.length, n = A[0].length;

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n / 2; j++) {
                int temp = A[i][j];
                A[i][j] = A[i][n - 1 - j] ^ 1;
                A[i][n - 1 - j] = temp ^ 1;

BiruLyu

class Solution {
    public int countSubstrings(String s) {
        if (s == null || s.length() < 0) return 0;
        int count = 0, len = s.length();
        boolean[][] isPalindrome = new boolean[len][len];
        for (int i = len - 1; i >= 0; i--) {
            for (int j = i; j < len; j++) {
                if (s.charAt(i) == s.charAt(j) && (j - i < 2 || isPalindrome[i + 1][j - 1])) {
                    isPalindrome[i][j] = true;
                    count++;

BiruLyu

class Solution {
    public List<List<Integer>> largeGroupPositions(String S) {
        List<List<Integer>> res = new ArrayList<>();
        int len = S.length();
        if (len < 3) return res;
        int start = 0, end = 1;
        while (end < len)  {
            while (end < len && S.charAt(end) == S.charAt(end - 1)) {
                end++;
            }

BiruLyu

class Solution {
    public String maskPII(String S) {
        StringBuilder res = new StringBuilder();
        int idx = S.indexOf('@');
        int len = S.length();
        if (idx > 0) {
            res.append(Character.toLowerCase(S.charAt(0)));
            res.append("*****");
            res.append(S.substring(idx - 1).toLowerCase());
        } else {

BiruLyu

class Solution {
	    public int uniqueLetterString(String S) {
	        char[] s = S.toCharArray();
	        int n = s.length;
	        int mod = 1000000007;
	        long ret = 0;
	        for(int i = 0;i < s.length;i++){
	        	int l = i-1;
	        	for(;l >= 0 && s[l] != s[i];l--);
	        	int r = i+1;

BiruLyu

public class Solution {
    public List<String> wordBreak(String s, List<String> wordDict) {
        List<String> res = new ArrayList<String>();
        if (s == null || s.length() == 0) {
            return res;
        }
        int max = 0;
        for (String str : wordDict) {
            max = Math.max(str.length(), max);
        }