Submission #4030713

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Source Code Expand

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include <stack>
#include <cstring>
using namespace std;
const int MAXN = 1e5 + 10;
inline void _read(int &x)
{
	x = 0;
	char t = getchar();
	while (!isdigit(t)) t = getchar();
	while (isdigit(t))
	{
		x = x * 10 + t - '0';
		t = getchar();
	}
}
int n;
int deg[MAXN];
vector <int> G[MAXN];
int q[MAXN];
char s[MAXN];
bool del[MAXN];
#define tp(x) (deg[x]&1)^(s[x]=='W')
#define val(x) (tp(x)==1?-2:0)
inline void toposort()
{
	register int head(1), tail(0);
	for (register int i = 1; i <= n; ++i)
		if (s[i] == 'B' && deg[i] == 1) q[++tail] = i;
	while (head <= tail)
	{
		register int cur = q[head++];
		del[cur] = true;
		for (auto v : G[cur])
		{
			if (deg[v]) --deg[v];
			if (s[v] == 'B' && deg[v] == 1 && !del[v]) q[++tail] = v;
		}
	}
}
int minn = 2147483647;
int tot = -2;
int f[MAXN];
inline void dfs(int x, int fa)
{
	tot += (tp(x) == 1) + 2;
	f[x] = val(x);
	for (auto v : G[x])
	{
		if (v != fa && !del[v])
		{
			dfs(v, x);
			minn = min(minn, f[x] + f[v]);
			f[x] = min(f[x], f[v] + val(x));
		}
	}
}
int main(int argc, char **argv)
{
	_read(n);
	memset(deg, 0, sizeof deg);
	for (register int i = 1; i < n; ++i)
	{
		register int u, v;
		_read(u), _read(v);
		G[u].push_back(v);
		G[v].push_back(u);
		++deg[u], ++deg[v];
	}
	scanf("%s", s + 1);
	toposort();
	for (register int i = 1; i <= n; ++i)
	{
		if (!del[i])
		{
			dfs(i, 0);
			printf("%d\n", minn + tot);
			return 0;
		}
	}
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main(int, char**)’:
./Main.cpp:75:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s", s + 1);
                    ^

Judge Result