链式前向星

import java.util.Scanner;

public class AdjacencyTable {

// 节点个数
private int n;

// 边的个数
private int m;

// 边的编号，从1开始
private int edgeSerial = 0;

// lastEdge[i] 保存以 i 为起点的最后一条边的编号
private int[] lastEdge;

// 所有的边
private Edge[] edges;

static class Edge {

// 边的终点
int end;

// 边的权重
int weight;

// 与该边同起点的上一条边的编号
int previous;

public Edge(int end, int weight, int previous) {
this.end = end;
this.weight = weight;
this.previous = previous;
}
}

public AdjacencyTable(int n, int m) {
this.n = n;
this.m = m;
}

public void init() {
lastEdge = new int[n + 1];
edges = new Edge[m + 1];
}

public void add(int a, int b, int weight) {
edges[++ edgeSerial] = new Edge(b, weight, lastEdge[a]);
lastEdge[a] = edgeSerial;
}

public void visit(int x) {
for (int i = lastEdge[x]; i != 0; i = edges[i].previous) {
System.out.println(x + "--->" + edges[i].end + " weight = " + edges[i].weight);
}
}

public void print() {

for (int i = 1; i <= n; ++ i) {
visit(i);
}

}

public static void main(String[] args) {
Scanner in = new Scanner(System.in);

while (in.hasNext()) {
int n = in.nextInt();
int m = in.nextInt();
AdjacencyTable table = new AdjacencyTable(n , m);
table.init();

while (m -- > 0) {
int a = in.nextInt();
int b = in.nextInt();
int weight = in.nextInt();
table.add(a, b, weight);
}

table.print();

}
}
}