Submission #3040773

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Source Code Expand

#include <iostream>
#include <fstream>
#include <cmath>  
#include <cstdlib>
#include <ctime>
#include <algorithm>
#include <numeric>
#include <functional>
#include <string> 
#include <vector>
#include <bitset>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>

using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;

#define REP(i,n) for(int i = 0; i < int(n); i++)
#define REREP(i,n) for(int i = int(n - 1); i >= 0; i--)
#define FOR(i, m, n) for(int i = int(m);i < int(n);i++)
#define REFOR(i, m, n) for(int i = int(n - 1);i >= int(m);i--)
#define ALL(obj) (obj).begin(),(obj).end()
#define fi first 
#define se second

#define VI vector<int>
#define VVI vector<vector<int>>
#define VVVI vector<vector<vector<int>>>
#define VD vector<double>
#define VVD vector<vector<double>>
#define VVVD vector<vector<vector<double>>>
#define VL vector<ll>
#define VVL vector<vector<ll>>
#define VVVL vector<vector<vector<ll>>>
#define VB vector<bool>
#define VVB vector<vector<bool>>
#define VVVB vector<vector<vector<bool>>>
#define VS vector<string>
#define VVS vector<vector<string>>
#define VVVS vector<vector<vector<string>>>

#define PII pair<int,int>
#define PDD pair<double,double>
#define PLL pair<ll,ll>
#define VPII vector<pair<int,int>>
#define VVPII vector<vector<pair<int,int>>>
#define VVVPII vector<vector<vector<pair<int,int>>>>
#define VPLL vector<pair<ll,ll>>
#define VVPLL vector<vector<pair<ll,ll>>>
#define VVVPLL vector<vector<vector<pair<ll,ll>>>>

const ll MOD = (ll)1e9 + 7;
const ll HINF = (ll)1e18;
const ll LINF = (ll)1e9;
const long double PI = 3.1415926535897932384626433;


void YN(bool flag) {
	cout << ((flag) ? "YES" : "NO") << endl;
}

void Yn(bool flag) {
	cout << ((flag) ? "Yes" : "No") << endl;
}

void yn(bool flag) {
	cout << ((flag) ? "yes" : "no") << endl;
}

template<class T> class Union_Find {
public:
	vector<int> prnt;
	vector<int> rank;
	vector<T> dist;

	Union_Find(int N = 1):prnt(vector<int>(N)),rank(vector<int>(N,0)),dist(vector<int>(N, 0)) {
		for (int i = 0; i < N; ++i) prnt[i] = i;
	}

	int root(int x) {
		if (prnt[x] == x) {
			return x;
		}
		else {
			dist[x] += dist[prnt[x]];
			return prnt[x] = root(prnt[x]);
		}
	}

	T updated_dist(int x) {
		root(x);
		return dist[x];
	}

	bool same(int x, int y) {
		return root(x) == root(y);
	}

	bool merge(int x, int y, T w) {
		w += updated_dist(x); w -= updated_dist(y);
		x = root(x); y = root(y);
		if (x == y) return false;
		if (rank[x] < rank[y]) swap(x, y), w = -w;
		if (rank[x] == rank[y]) ++rank[x];
		prnt[y] = x;
		dist[y] = w;
		return true;
	}

	T diff(int x, int y) {
		return updated_dist(y) - updated_dist(x);
	}
};

int main() {
	int N, M;
	cin >> N >> M;
	Union_Find<int> uf(N);
	for (int i = 0; i < M; ++i) {
		int l, r, d;
		cin >> l >> r >> d;
		--l, --r;
		if (uf.same(l, r)) {
			if (d != uf.diff(l, r)) {
				cout << "No" << endl;
				return 0;
			}
		}
		else {
			uf.merge(l, r, d);
		}
	}
	cout << "Yes" << endl;
	return 0;
}

Submission Info

Judge Result