Language: Java

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {

	static PrintWriter out;
	static InputReader ir;
	static final long INF=Long.MAX_VALUE;

	static void solve() {
		int n=ir.nextInt();
		int m=ir.nextInt();
		Graph[] gs=new Graph[n];
		for(int i=0;i<n;i++)
			gs[i]=new Graph();
		int[] in=new int[n];
		for(int i=0;i<m;i++)){
			int l=ir.nextInt()-1;
			int r=ir.nextInt()-1;
			int d=ir.nextInt();
			gs[l].add(new int[]{r,d});
			in[r]++;
		}
		long[] di=new long[n];
		Arrays.fill(di, INF);
		Deque<Integer> s=new ArrayDeque<>();
		for(int i=0;i<n;i++)
			if(in[i]==0){
				s.offerFirst(i);
				di[i]=0;
			}
		int ct=0;
		while(!s.isEmpty()){
			int from=s.pollFirst();
			for(int j=0;j<gs[from].size();j++){
				ct++;
				int to=gs[from].get(j)[0];
				in[to]--;
				if(di[to]!=INF){
					if(di[from]+gs[from].get(j)[1]!=di[to]){
						out.println("No");
						return;
					}
				}
				else{
					di[to]=di[from]+gs[from].get(j)[1];
				}
				if(di[to]>(long)1e9){
					out.println("No");
					return;
				}
				if(in[to]==0){
					s.offerFirst(to);
				}
			}
		}
		out.println(ct==m?"Yes":"No");
	}

	static class Graph extends ArrayList<int[]>{}

	public static void main(String[] args) throws Exception {
		ir = new InputReader(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}

	static class InputReader {

		private InputStream in;
		private byte[] buffer = new byte[1024];
		private int curbuf;
		private int lenbuf;

		public InputReader(InputStream in) {
			this.in = in;
			this.curbuf = this.lenbuf = 0;
		}

		public boolean hasNextByte() {
			if (curbuf >= lenbuf) {
				curbuf = 0;
				try {
					lenbuf = in.read(buffer);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return false;
			}
			return true;
		}

		private int readByte() {
			if (hasNextByte())
				return buffer[curbuf++];
			else
				return -1;
		}

		private boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		private void skip() {
			while (hasNextByte() && isSpaceChar(buffer[curbuf]))
				curbuf++;
		}

		public boolean hasNext() {
			skip();
			return hasNextByte();
		}

		public String next() {
			if (!hasNext())
				throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (!isSpaceChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public int nextInt() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

		public long nextLong() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		public char[][] nextCharMap(int n, int m) {
			char[][] map = new char[n][m];
			for (int i = 0; i < n; i++)
				map[i] = next().toCharArray();
			return map;
		}
	}
}

Compiler output:
Main.java:24: error: illegal start of expression
		for(int i=0;i<m;i++)){
		                    ^
1 error