链式前向星

以起始点为划分依据，以边为基础单位。

Template

#include <bits/stdc++.h>
#define MAX 10005
using namespace std;

struct edge { int to, next, w; };
edge es[MAX];
int cnt, head[MAX];

void add(int u, int v, int w)
{
	es[++cnt].next = head[u];
	es[cnt].w = w;
	es[cnt].to = v;
	head[u] = cnt;
}

void print(int st) //以st为起始结点的边
{
	for (int i = head[st]; i != 0; i = es[i].next) 
		cout << st << " " << es[i].to << " " << es[i].w << endl;
}

int main()
{
	int n, m, u, v, w;
	cin >> n >> m;
	cnt = 0;
	for (int i = 1; i <= m; i++) {
		cin >> u >> v >> w;
		add(u, v, w);
	}
	for (int i = 1; i <= n; i++)
		print(i);
	return 0;
}

Test Data

4 3
1 2 3
1 3 4
1 4 5

4 4
1 2 3
1 3 4
1 4 5
2 3 3