abc12d.java

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.NoSuchElementException;
 
public class Main {
	static FastScanner sc=new FastScanner();
	static int INF=Integer.MAX_VALUE/2-1;
	static int src,dest,N,M,ai,bi,ti;
	static long[][] dist;
	public static void main(String[] args) {
		N=sc.nextInt();
		M=sc.nextInt();
		dist=new long[N][N];
		for(int i=0;i<N;i++){
			Arrays.fill(dist[i], INF);
			dist[i][i]=0;
		}
		for(int i=0;i<M;i++){
			ai=sc.nextInt()-1;
			bi=sc.nextInt()-1;
			ti=sc.nextInt();
			dist[ai][bi]=dist[bi][ai]=ti;
		}
//		src=sc.nextInt();
//		dest=sc.nextInt();
		Dijkstra di=new Dijkstra(N);
		di.setGraph(dist);
		long minOfMaxTime=INF;
		for(int i=0;i<N;i++){
			di.setPath(i);
			long[] res=di.getShortests();//O(n^2)
			long maxTime=-1;
			for(int j=0;j<N;j++){
				maxTime=Math.max(maxTime, res[j]);
			}
			minOfMaxTime=Math.min(minOfMaxTime, maxTime);
		}
		System.out.println(minOfMaxTime);
 
	}
 
}
 
//距離系はlong，要素数系はint
class Dijkstra{
	FastScanner sc=new FastScanner();
	private boolean[] decided;
	private long[][] dist;
	private final int N;
	int ai,bi,ti;
//	int src,dest;
	int src;
	public long INF=Long.MAX_VALUE/2-1;
	public Dijkstra(int n) {
		N=n;
	}
 
	public void setGraph(long[][] graph){
		dist=graph.clone();
	}
	public void setPath(int start){
		src=start;
//		dest=goal;
	}
 
	public long[] getShortests(){
		decided=new boolean[N];
		Arrays.fill(decided, false);
		decided[src]=true;
		int minIndex=-1;
		long min;
		while(!isFinished(decided)){
			min=INF;
			for(int i=0;i<N;i++){//決まっていないところで最小の場所を探す
				if(!decided[i]&&dist[src][i]<min){
					min=dist[src][i];
					minIndex=i;
				}
			}
			//更新
			if(minIndex==-1){
				System.out.println("indexError");
			}else{
				decided[minIndex]=true;
				for(int j=0;j<N;j++){
					dist[src][j]=Math.min(dist[src][j],
							dist[src][minIndex]+dist[minIndex][j]);
				}
			}
		}
		long[] res=new long[N];
		for(int i=0;i<N;i++){
			res[i]=dist[src][i];
		}
		return res;
	}
	public static boolean isFinished(boolean[] array){
		boolean uncheckedElem=true;
		for(int i=0;i<array.length;i++){
			if(array[i]==false){
				uncheckedElem=false;
				break;
			}
		}
		return uncheckedElem;
	}
}
 
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
    public boolean hasNext() { skipUnprintable(); return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        if (!hasNext()) throw new NoSuchElementException();
        int n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
}