Java朴素Prim MLE

import java.io.*;
import java.util.Arrays;

public class Main {
    static PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));

    public static final int N = 5010, INF = 0x3f3f3f3f;
    static int n, m;
    static int[][] g = new int[N][N]; // 92MB
    static int[] dist = new int[N]; //  19 MB
    static boolean[] vis = new boolean[N]; // 19MB

    public static void main(String[] args) throws Exception{
        n = getInt(); m = getInt();

        for (int[] gi : g) Arrays.fill(gi, (int) 1e10);

        while (m-- > 0) {
            int a = getInt(), b = getInt(), c = getInt();
            g[a][b] = g[b][a] = Math.min(g[a][b], c);
        }

        long t = prim();

        if (t == INF) pw.println("orz");
        else pw.println(t);

        pw.flush();
    }

    public static long prim() {
        Arrays.fill(dist, (int) 1e10);

        long res = 0;
        for (int i = 0; i < n; i++) {
            int t = -1;
            for (int j = 1; j <= n; j++) {
                if (!vis[j] && (t == -1 || dist[t] > dist[j])) {
                    t = j;
                }
            }

            if (i != 0 && dist[t] == INF) return INF;
            if (i != 0) res += dist[t];

            for (int j = 1; j <= n; j++) {
                dist[j] = Math.min(dist[j], g[t][j]);
            }

            vis[t] = true;
        }

        return res;
    }

    public static int getInt() throws Exception {
        st.nextToken();
        return (int) st.nval;
    }
}