求助

#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <stack>

using namespace std;
#define ll long long

const int N = 5e5 + 10;
const int INF = 0x7fffffff;

struct edge
{
    int weight, next_v;
};

vector<edge> graph[N];

int _begin, now_node_index, n, m;
int dis[N], pre[N];
bool vis[N];

void init()
{
    int i;
    for (i = 0; i < N; i++)
    {
        dis[i] = INF;
    }
}

void build()
{
    int i;
    cin >> n >> m >> _begin;
    for (i = 0; i < m; i++)
    {
        int x, y, w;
        cin >> x >> y >> w;
        graph[x].push_back({w, y});
    }
}
int main()
{
    int i, j;
    build();
    init();
    dis[_begin] = 0;
    now_node_index = _begin;
    for (i = 0; i < n; i++)
    {
        now_node_index = -1;
        int _min = INF;
        for (j = 0; j < n; j++)
        {
            if (!vis[j] && dis[j] < _min)
            {
                now_node_index = j;
                _min = dis[j];
            }
        }
        vis[now_node_index] = 1;
        for (j = 0; j < graph[now_node_index].size(); j++)
        {
            int temp_node = graph[now_node_index][j].next_v;
            if (vis[temp_node])
            {
                continue;
            }
            if (graph[now_node_index][j].weight + dis[now_node_index] < dis[temp_node])
            {
                dis[temp_node] = graph[now_node_index][j].weight + dis[now_node_index];
                pre[j] = now_node_index;
            }
        }
    }
    for (i = 1; i <= n; i++)
    {
        cout << dis[i] << ' ';
    }
    return 0;
}