Submission #82628

#	Time	Username	Problem	Language	Result	Execution time	Memory
82628		Good	Min-max tree (BOI18_minmaxtree)	C++11	100 / 100	366 ms	67244 KiB

minmaxtree

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
 
#define ff first
#define ss second
#define Maxn 70009
#define ll long long
#define pb push_back
#define Inf 1000000009
#define ppb() pop_back()
#define pii pair <int , int>
#define mid(x, y) (x + y) / 2
#define all(x) x.begin(),x.end()
#define llInf 1000000000000000009
#define tr(i, c) for(__typeof(c).begin() i = (c).begin() ; i != (c).end() ; i++)
using namespace std;
using namespace __gnu_pbds;
typedef tree <int, null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update> order;

char c[Maxn]; 
bool vis[Maxn];
 
int n, q;
int T[Maxn];
int lvl[Maxn];
int mat[Maxn][20];
int l[Maxn], r[Maxn];
int E[Maxn][2], P[Maxn][2];
int x[Maxn], y[Maxn], z[Maxn];
 
vector <int> M[Maxn];
vector <int> adj[Maxn];
vector <pair <int, pair <int, pii> > > A[2];
 
map <int, int> mp;
 
void dfs (int nd, int p, int d) {
	mat[nd][0] = p;
	lvl[nd] = lvl[p] + 1;
	
	if (d == 1 and nd != 1) {
		if (E[nd][0])
			M[nd].pb (E[nd][0]);
				
		if (E[nd][1])
			M[nd].pb (E[nd][1]);
	}
	
	if (d == 2 and nd != 1) {
		if (!l[nd])
			printf ("%d %d %d\n", p, nd, T[E[nd][1]]);
		else
			printf ("%d %d %d\n", p, nd, T[l[nd]]);	
	}
	
	for (auto i: adj[nd])
		if (i != p)		
			dfs (i, nd, d);
}
 
bool dfs1 (int nd) {
	if (vis[nd])
		return 0;
	
	vis[nd] = 1;	
	for (auto i: M[nd])
		if (!r[i] or dfs1 (r[i])) {
			l[nd] = i;
			r[i] = nd;
			return 1;
		}
	
	return 0;	
} 
 
void build () {
	for (int i = 1; i <= 18; i++)
		for (int j = 1; j <= n; j++)
			if (mat[j][i - 1] != -1)
				mat[j][i] = mat[mat[j][i - 1]][i - 1];	
}
 
int LCA (int a, int b) {
	if (lvl[a] < lvl[b])
		swap (a, b);
		
	for (int i = 18; i >= 0; i--)
		if (lvl[mat[a][i]] >= lvl[b])
			a = mat[a][i];
		
	if (a == b)
		return a;
	
	for (int i = 18; i >= 0; i--)
		if (mat[a][i] != -1 and mat[a][i] != mat[b][i])
			a = mat[a][i], b = mat[b][i];
		
	return mat[a][0];					
}
 
int dsu (int x, bool d) {
	if (P[x][d] == x)
		return x;	
	
	return P[x][d] = dsu (P[x][d], d);	
}
 
void solve (int x, int y, int z, bool d) {
	x = dsu (P[x][d], d);
			
	if (lvl[x] <= lvl[y])
		return;		
	
	E[x][d] = z;
	
	if (mat[x][0] != -1)
		P[x][d] = dsu (mat[x][0], d);
	
	x = P[x][d];
	
	solve (x, y, z, d);	
}
 
int main () {
	//freopen ("file.in", "r", stdin);
	//freopen ("file.out", "w", stdout);
	
 	//srand ((unsigned) time ( NULL ));
	//int randomNumber = rand() % 10 + 1;
 
	scanf ("%d", &n);
	for (int i = 1; i < n; i++) {
		int u, v;
		scanf ("%d%d", &u, &v);
		
		adj[u].pb (v);
		adj[v].pb (u);
		P[i][0] = P[i][1] = i;
	}
	
	P[n][0] = P[n][1] = n;
	
	memset (mat, -1, sizeof (mat));
	dfs (1, -1, 0);
	build ();
	
	scanf ("%d", &q);
	
	for (int i = 1; i <= q; i++) {		
		scanf (" %c%d%d%d", &c[i], &x[i], &y[i], &z[i]);
		mp[z[i]] = 1;	
	}
	
	int cnt = 0;
	for (auto i: mp)
		mp[i.ff] = ++cnt;
	
	for (int i = 1; i <= q; i++) {
		int l = LCA (x[i], y[i]);
		
		if (c[i] == 'M')
			A[0].pb ({mp[z[i]], {l, {x[i], y[i]}}});
		else
			A[1].pb ({mp[z[i]], {l, {x[i], y[i]}}});		
		
		T[mp[z[i]]] = z[i];
	}
	
	sort (all (A[0]));
	sort (all (A[1]));
	reverse (all (A[1]));
	
	for (auto i: A[0]) {
		solve (i.ss.ss.ff, i.ss.ff, i.ff, 0);
		solve (i.ss.ss.ss, i.ss.ff, i.ff, 0);	
	}
		
	for (auto i: A[1]) {
		solve (i.ss.ss.ff, i.ss.ff, i.ff, 1);
		solve (i.ss.ss.ss, i.ss.ff, i.ff, 1);
	}
	
	dfs (1, -1, 1);
	
	bool ok = 1;
	while (ok) {
		ok = 0;
		memset (vis, 0, sizeof (vis));
		
		for (int i = 2; i <= n; i++)
			if (!l[i] and dfs1 (i))
				ok = 1;
	}

	dfs (1, -1, 2);	
	return 0;
}

Compilation message (stderr)

minmaxtree.cpp: In function 'int main()':
minmaxtree.cpp:131:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d", &n);
  ~~~~~~^~~~~~~~~~
minmaxtree.cpp:134:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d%d", &u, &v);
   ~~~~~~^~~~~~~~~~~~~~~~
minmaxtree.cpp:147:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d", &q);
  ~~~~~~^~~~~~~~~~
minmaxtree.cpp:150:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf (" %c%d%d%d", &c[i], &x[i], &y[i], &z[i]);
   ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 22 / 22
• Subtask 3: 29 / 29
• Subtask 4: 42 / 42