#include <bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f3f
const int M = 2e5 + 5;
const int N = 1e3 + 5;
int n, m, x;
bool vis[N];
int dis[M];
int ans;
struct node {
	int pos;
	int dis;
	bool operator<(node x)const {
		return dis > x.dis;
	}
	node(int a, int b): pos(a), dis(b) {}
};
priority_queue<node>q;
struct edge {
	int to;
	int dis;
	int nxt;
};
edge e[M];
int head[M];
int cnt;
void add(int u, int v, int w) {
	cnt++;
	e[cnt].dis = w;
	e[cnt].to = v;
	e[cnt].nxt = head[u];
	head[u] = cnt;
}
void dijkstra(int s) {
	dis[s] = 0;
	q.push(node(s, 0));
	while (!q.empty()) {
		int u = q.top().pos;
		q.pop();
		if (vis[u])
			continue;
		vis[u] = 1;
		for (int i = head[u]; i; i = e[i].nxt) {
			int v = e[i].to;
			if (dis[v] > dis[u] + e[i].dis) {
				dis[v] = dis[u] + e[i].dis;
				if (!vis[v])
					q.push(node(v, dis[v]));
			}
		}
	}
}
int main(void) {
	scanf("%d %d %d", &n, &m, &x);
	for (int i = 1; i <= 2 * n; ++i)
		dis[i] = inf;
	for (int i = 1; i <= m; ++i) {
		int u, v, w;
		scanf("%d %d %d", &u, &v, &w);
		printf("%d %d %d %d\n", i, u, v, w);
		add(u, v, w);
		add(v + n, u + n, w);
	}
	dijkstra(x);
	dijkstra(n + x);
	for (int i = 1; i <= n; ++i)
		ans = max(ans, dis[i] + dis[i + n]);
	printf("%d", ans);
	return 0;
}

对于此段代码，第二个测试点会导致数据读入不全

1000条边，只能读入289条，但是读入的第289条边确实是输入的第1000条边

无法解决，求助dalao