每日一道算法题之建图

import java.util.ArrayList;
import java.util.Arrays;
 
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
 
    public static int n = 11;
    public static int m = 31;
 
    // 矩阵-有方向-无权-权重默认都为1.
    public static int[][] graph_direct_noweight = new int[n][n];
 
    // 矩阵-有方向-有权
    public static int[][] graph_direct_weight = new int[n][n];
 
    // 矩阵-无方向(双向)-无权
    public static int[][] graph_nodirect_noweight = new int[n][n];
 
    // 矩阵-无方向(双向)-有权
    public static int[][] graph_nodirect_weight = new int[n][n];
 
    // 邻接表-有方向-无权
 
    public static ArrayList<ArrayList<Integer>> map_direct_noweight;
 
    // 邻接表-有方向-有权
    public static ArrayList<ArrayList<int[]>> map_direct_weight = new ArrayList<>();
 
    // 邻接表-无方向-无权
    public static ArrayList<ArrayList<Integer>> map_nodirect_noweight;
 
    // 邻接表-无方向-有权
    public static ArrayList<ArrayList<int[]>> map_nodirect_weight;
 
    public static void build(int n) {
 
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                graph_direct_weight[i][j] = 0;
            }
        }
        map_direct_weight.clear();
        for (int i = 0; i <= n; i++) {
            map_direct_weight.add(new ArrayList<int[]>());
        }
 
    }
 
    public static void main(String[] args) {
        // 理解了带权图的建立过程，也就理解了不带权图
        // 点的编号为1...n
        // 例子1自己画一下图，有向带权图，然后打印结果
        int n1 = 4;
        int[][] edges1 = { { 1, 3, 6 }, { 4, 3, 4 }, { 2, 4, 2 }, { 1, 2, 7 }, { 2, 3, 5 }, { 3, 1, 1 } };
        build(n1);
        directGraph(edges1);
        traversal(n1);
    }
 
    private static void traversal(int n1) {
        System.out.println("邻接矩阵: 遍历图");
        for (int i = 1; i <= n1; i++) {
            for (int j = 1; j <= n1; j++) {
                if (graph_direct_weight[i][j] != 0) {
                    System.out.println(i + " to " + j + " weight : " + graph_direct_weight[i][j]);
                }
            }
        }
 
        System.out.println("邻接表: 遍历图");
        for (int i = 1; i <= n1; i++) {
            ArrayList<int[]> array = map_direct_weight.get(i);
            for (int[] js : array) {
                System.out.println(i + " to " + js[0] + " weight : " + js[1]);
            }
 
        }
    }
 
    private static void directGraph(int[][] edges1) {
        for (int i = 0; i < edges1.length; i++) {
            // 邻接矩阵-带权重-有方向
            graph_direct_weight[edges1[i][0]][edges1[i][1]] = edges1[i][2];
            // 邻接表-带权重-有方向
            map_direct_weight.get(edges1[i][0]).add(new int[] { edges1[i][1], edges1[i][2] });
        }
    }
 
}