树与图的深搜与广搜模板

树与图的深搜与广搜模板

一.图的存储

二.模板

深搜:

广搜:

import java.util.*;
public class Main{
     
    static int[] h = new int[100010];
    static int[] nodes = new int[100010];
    static int[] next = new int[100010];
    static boolean[] vis = new boolean[100010];
    static int[] dist = new int[100010];
    static int[] q = new int[100010];
    static int index = 1;
    static void add(int a,int b){
     
        nodes[index] = b;
        next[index] = h[a];
        h[a] = index++;
    }
    public static void main(String[] agrs){
     
        Scanner scan = new Scanner(System.in);
        int n,m;
        n = scan.nextInt();
        m = scan.nextInt();
        int a,b;
        for(int i=1;i<=n;i++){
     
            h[i] = -1;
        }
        for(int i=1;i<=m;i++){
     
            a = scan.nextInt();
            b = scan.nextInt();
            add(a,b);
        }
        int head = 0;
        int tail = 0;
        q[head] = 1;
        dist[1] = 0;
        vis[1] = true;
        while(head<=tail){
     
            int t = q[head++];
            for(int i = h[t];i!=-1;i=next[i]){
     
                int ss = nodes[i];
                if(!vis[ss]){
     
                        dist[ss] = dist[t]+1;
                        q[++tail] = ss;
                        vis[ss] = true;
                }
            }
        }
        if(dist[n]==0){
     
            System.out.print(-1);
        }else{
     
            System.out.print(dist[n]);
        }
    }
}