D - Coloring Edges on Tree

Problem link: Coloring Edges on Tree

Explanation: GfG

Implementation:

	#include <bits/stdc++.h>
	using namespace std;
	#define INF 1<<30
	#define endl '\n'
	#define maxn 100005
	#define tc printf("Case %d: ", cs)
	#define tcn printf("Case %d:\n", cs);
	#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	typedef long long ll;
	const double PI = acos(-1.0);
	#define dbg1(x) cerr << #x << " = " << x << endl;
	#define dbg2(x, y) cerr << #x << " = " << x << ", " << #y << " = " << y << endl;
	#define dbg3(x, y, z) cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z << " = " << z << endl;
	#define dbg4(w,x, y, z) cerr << #w << " = " << w << ", " <<#x << " = " << x << ", " << #y << " = " << y << ", " << #z << " = " << z << endl;
	template < typename F, typename S >
	ostream& operator << ( ostream& os, const pair< F, S > & p ) {
	return os << "(" << p.first << ", " << p.second << ")";
	}
	template < typename T >
	ostream &operator << ( ostream & os, const vector< T > &v ) {
	os << "{";
	for (auto it = v.begin(); it != v.end(); ++it) {
	if ( it != v.begin() ) os << ", ";
	os << *it;
	}
	return os << "}";
	}
	template < typename T >
	ostream &operator << ( ostream & os, const set< T > &v ) {
	os << "[";
	for (auto it = v.begin(); it != v.end(); ++it) {
	if ( it != v.begin()) os << ", ";
	os << *it;
	}
	return os << "]";
	}
	template < typename F, typename S >
	ostream &operator << ( ostream & os, const map< F, S > &v ) {
	os << "[";
	for (auto it = v.begin(); it != v.end(); ++it) {
	if ( it != v.begin() ) os << ", ";
	os << it -> first << " = " << it -> second ;
	}
	return os << "]";
	}
	#define dbg(args...) do {cerr << #args << " : "; faltu(args); } while(0)
	clock_t tStart = clock();
	#define timeStamp dbg("Execution Time: ", (double)(clock() - tStart)/CLOCKS_PER_SEC)
	void faltu () { cerr << endl; }
	template <typename T>
	void faltu( T a[], int n ) {
	for (int i = 0; i < n; ++i) cerr << a[i] << ' ';
	cerr << endl;
	}
	template <typename T, typename ... hello>
	void faltu( T arg, const hello &... rest) { cerr << arg << ' '; faltu(rest...); }
	// Program showing a policy-based data structure.
	#include <ext/pb_ds/assoc_container.hpp> // Common file
	#include <ext/pb_ds/tree_policy.hpp>
	#include <functional> // for less
	#include <iostream>
	using namespace __gnu_pbds;
	using namespace std;
	// GNU link : https://goo.gl/WVDL6g
	typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
	tree_order_statistics_node_update>
	new_data_set;
	/**___________________________________________________**/
	const int N = 1e5 + 5;
	int clr = 0;
	void colorEdges(int ptr, vector<vector<pair<int, int> > >& gra,
	vector<int>& edgeColors, bool isVisited[])
	{
	queue<int> q;
	int c = 0;
	set<int> colored;
	// return if isVisited[ptr] is true
	if (isVisited[ptr])
	return;
	// Mark the current node visited
	isVisited[ptr] = 1;
	// Traverse all edges of current vertex
	for (int i = 0; i < (int) gra[ptr].size(); i++) {
	// if already colored, insert it into the set
	if (edgeColors[gra[ptr][i].second] != -1)
	colored.insert(edgeColors[gra[ptr][i].second]);
	}
	for (int i = 0; i < (int) gra[ptr].size(); i++) {
	// if not visited, inset into the queue
	if (!isVisited[gra[ptr][i].first])
	q.push(gra[ptr][i].first);
	if (edgeColors[gra[ptr][i].second] == -1) {
	// if col vector -> negative
	while (colored.find(c) != colored.end())
	// increment the color
	c++;
	// copy it in the vector
	edgeColors[gra[ptr][i].second] = c;
	// then add it to the set
	colored.insert(c);
	c++;
	clr = max(clr, c);
	}
	}
	// while queue's not empty
	while (!q.empty()) {
	int temp = q.front();
	q.pop();
	colorEdges(temp, gra, edgeColors, isVisited);
	}
	return;
	}
	int main()
	{
	FASTIO
	#ifndef ONLINE_JUDGE
	freopen("in.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
	freopen("error.txt", "w", stderr);
	#endif
	//*/
	vector<vector<pair<int, int> > > graph;
	vector<int> edgeColors;
	bool isVisited[N] = { 0 };
	int n;
	cin >> n;
	graph.resize(n);
	edgeColors.resize(n - 1, -1);
	for (int i = 0; i < n-1 ; i++) {
	int u, v;
	cin >> u >> v;
	--u;
	--v;
	graph[u].push_back(make_pair(v, i));
	graph[v].push_back(make_pair(u, i));
	}
	colorEdges(0, graph, edgeColors, isVisited);
	cout << clr << endl;
	for (int i = 0; i < n-1; i++)
	cout << edgeColors[i] + 1 << "\n";
	return 0;
	}

view raw edgeColor.cpp hosted with ❤ by GitHub

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