AcWing 860.Dyeing to judge Bipartite Graph(Dyeing) Described by Java

Cause of the changing of memory, this problem can be solved. It’s about Bipartite Graph.

Principle is if a pic is a bipartite graph just when there is no odd ring in.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;

public class Main {
          
   
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter pw = new PrintWriter(System.out);

    static int N = 100010, n, m;
    static int h[] = new int[N << 1], e[] = new int[N << 1], ne[] = new int[N << 1], idx;
    static int color[] = new int[N << 1];

    public static void add(int a, int b) {
          
   
        e[idx] = b;
        ne[idx] = h[a];
        h[a] = idx++;
    }

    public static void main(String[] args) throws IOException {
          
   
        String[] s = br.readLine().split(" ");
        n = Integer.parseInt(s[0]);
        m = Integer.parseInt(s[1]);
        Arrays.fill(h, -1);
        for (int i = 0; i < m; i++) {
          
   
            s = br.readLine().split(" ");
            int a = Integer.parseInt(s[0]);
            int b = Integer.parseInt(s[1]);
            add(a, b);
            add(b, a);
        }

        boolean flag = true;
        for (int i = 1; i <= n; i++) {
          
   
            if (color[i] == 0) {
          
   
                if (!dfs(i, 1)) {
          
   
                    flag = false;
                    break;
                }
            }
        }

        if (!flag) pw.println("No");
        else pw.println("Yes");

        pw.flush();
        br.close();
    }

    private static boolean dfs(int u, int c) {
          
   
        color[u] = c;
        for (int i = h[u]; i != -1; i = ne[i]) {
          
   
            int j = e[i];
            if (color[j] == 0) {
          
   
                if (!dfs(j, 3 - c)) 
                    return false;
            } 
            else if (color[j] == c) return false;
        }
        return true;
    }
}