Leet Code 785. Is Graph Bipartite

package pep.Day41;

import java.util.*;

// method of alternate color code

public class LeetCode_Is_Graph_Bipartite_1 {
    public static void main(String[] args) {
        //int[][] graph = {{1, 2, 3}, {0, 2}, {0, 1, 3}, {0, 2}};
        int[][] graph = {{1, 3}, {0, 2}, {1, 3}, {0, 2}};
        System.out.println(isBipartite(graph));
        System.out.println(isBipartite2(graph));
    }

    public static boolean isBipartite2(int[][] graph) {
        //BFS
        // 0(not meet), 1(black), 2(white)
        int[] visited = new int[graph.length];

        for (int i = 0; i < graph.length; i++) {
            if (graph[i].length != 0 && visited[i] == 0) {
                visited[i] = 1;
                Queue<Integer> q = new LinkedList<>();
                q.offer(i);
                while (!q.isEmpty()) {
                    int current = q.poll();
                    for (int c : graph[current]) {
                        // ADD ALTERNATE COLOR CODE
                        if (visited[c] == 0) {
                            visited[c] = (visited[current] == 1) ? 2 : 1;
                            q.offer(c);
                        } else {

                            // COLOR OF CHILD AND PARENT NODE SHOULD NOT BE SAME
                            if (visited[c] == visited[current]) 

                                return false;
                        }
                    }
                }

            }
        }

        return true;
    }

    public static boolean isBipartite(int[][] graph) {
        int[] visited = new int[graph.length];
        Arrays.fill(visited, -1);

        for (int i = 0; i < visited.length; i++) {
            if (visited[i] == -1)
                if (!dfs(graph, i, visited))
                    return false;

        }

        return true;
    }

    public static boolean dfs(int[][] graph, int src, int[] visited) {
        Queue<Integer> queue = new LinkedList<>();
        queue.add(src);
        int level = 0;

        while (!queue.isEmpty()) {
            int size = queue.size();

            while (size-- > 0) {

                int out = queue.remove();
                // pehle se visited me present hai
                if (visited[out] != -1) {
                    // conflict check krenge
                    if (visited[out] % 2 != level % 2)
                        return false;

                }
                // yha tak pauche to visited nhi tha
                visited[out] = level;

                for (int nbr : graph[out])
                    if (visited[nbr] == -1)
                        queue.add(nbr);
            }
            level++;
        }
        return true;
    }


}