Submission #2502431

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Source Code Expand

#include <bits/stdc++.h>
// iostream is too mainstream
#include <cstdio>
// bitch please
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <cmath>
#include <iomanip>
#include <time.h>
#define dibs reserve
#define OVER9000 1234567890
#define ALL_THE(CAKE,LIE) for(auto LIE =CAKE.begin(); LIE != CAKE.end(); LIE++)
#define tisic 47
#define soclose 1e-8
#define chocolate win
// so much chocolate
#define patkan 9
#define ff first
#define ss second
#define abs(x) ((x < 0)?-(x):x)
#define uint unsigned int
#define dbl long double
#define pi 3.14159265358979323846
using namespace std;
// mylittledoge

typedef long long cat;

#ifdef DONLINE_JUDGE
	// palindromic tree is better than splay tree!
	#define lld I64d
#endif

void DFS(int R, int par, vector< vector<int> > &G, vector<int> &cov, string &S) {
	ALL_THE(G[R], it) if(*it != par) {
		DFS(*it, R, G, cov, S);
		if(cov[*it]) cov[R] = 1;
	}
	if(S[R] == 'W') cov[R] = 1;
}

int DFS_maxcost(int R, int par, vector< vector<int> > &G, vector<int> &cost, vector<int> &maxcost) {
	int maxcost_down = 0;
	ALL_THE(G[R], it) if(*it != par) {
		int cost_down = DFS_maxcost(*it, R, G, cost, maxcost);
		maxcost[R] = max(maxcost[R], cost_down + maxcost_down + cost[R]);
		maxcost_down = max(maxcost_down, cost_down);
	}
	return maxcost_down + cost[R];
}

int main() {
	cin.sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(10);
	int N;
	cin >> N;
	vector< vector<int> > G(N);
	for(int i = 0; i < N-1; i++) {
		int u, v;
		cin >> u >> v;
		G[--u].push_back(--v);
		G[v].push_back(u);
	}
	string S;
	cin >> S;

	int R = -1;
	for(int i = 0; i < N; i++) if(S[i] == 'W') R = i;
	if(R == -1) {
		cout << "0\n";
		return 0;
	}

	vector<int> cov(N, 0);
	DFS(R, R, G, cov, S);
	vector<int> fail(N, 0);
	for(int i = 0; i < N; i++) if(S[i] == 'W') fail[i] = 1;
	for(int i = 0; i < N; i++) ALL_THE(G[i], it)
		if(cov[i] && cov[*it]) fail[i] = 1-fail[i];

	vector<int> maxcost(N, 0);
	DFS_maxcost(R, R, G, fail, maxcost);

	int ans = 0;
	for(int i = 0; i < N; i++) ALL_THE(G[i], it)
		if(cov[i] && cov[*it]) ans++;
	for(int i = 0; i < N; i++) if(fail[i]) ans++;
	int maxcost_total = 0;
	for(int i = 0; i < N; i++) maxcost_total = max(maxcost_total, maxcost[i]);
	ans -= 2 * maxcost_total;
	if(ans <= 0) ans = 1;
	cout << ans << "\n";
	return 0;}

// look at my code
// my code is amazing

Submission Info

Judge Result