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题意
题解
代码
#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;
typedef double db;
typedef long long ll;
typedef unsigned long long ull;
const int nmax = 1e6+7;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const ull p = 67;
const ull MOD = 1610612741;
int head[nmax], tot, tot2, head2[nmax];
int dfn[nmax], low[nmax], color[nmax], ss[nmax], st, scc, dfs_clock;
int in[nmax], opp[nmax], ban[nmax];
bool instack[nmax];
queue<int> q;
struct edge{
int to, nxt;
}e[nmax<<1], e2[nmax<<1];
void add_edge(int u, int v) {
e[tot].to = v;
e[tot].nxt = head[u];
head[u] = tot++;
}
void add_edge2(int u, int v) {
e2[tot2].to = v;
e2[tot2].nxt = head2[u];
head2[u] = tot2++;
}
void init() {
memset(head, -1, sizeof head);
memset(head2, -1, sizeof head2);
memset(dfn, 0, sizeof dfn);
memset(low, 0, sizeof low);
memset(color, 0, sizeof color);
memset(ban, 0 ,sizeof ban);
memset(in, 0, sizeof in);
memset(opp, 0, sizeof opp);
st = scc = dfs_clock = tot2 = tot = 0;
}
void topo(int u) {
q.push(u);
in[u] = -1;
for(int i = head2[u] ; i != -1; i = e2[i].nxt) {
int v = e2[i].to;
in[v] -- ;
if(!in[v])
topo(v);
}
}
void tarjan(int u) {
low[u] = dfn[u] = ++ dfs_clock;
ss[st++] = u;
instack[u] = true;
for(int i = head[u] ; i != -1; i = e[i].nxt) {
int v = e[i].to;
if(!dfn[v]) {
tarjan(v);
low[u] = min(low[u], low[v]);
} else if(instack[v]) {
low[u] = min(low[u], dfn[v]);
}
}
if(low[u] == dfn[u]) {
scc ++;
int tmp;
for(;;) {
tmp = ss[--st];
color[tmp] = scc;
instack[tmp] = false;
if(tmp == u)
break;
}
}
}
int n, m;
int main(){
while(scanf("%d %d", &n, &m)!= EOF) {
if(n == 0 && m == 0)
break;
init();
int u, v, ou, ov;
char cu, cv;
for(int i = 1; i <= m; ++i) {
scanf("%d%c%d%c", &u, &cu, &v, & cv);
if(cu == 'h')
u = (u << 1) +1;
else
u = (u << 1);
ou = u ^ 1;
if(cv == 'h')
v = (v << 1) + 1;
else
v = (v << 1);
ov = v ^ 1;
add_edge(u, ov);
add_edge(v, ou);
}
add_edge(0, 1);
for(int i = 0; i < 2 * n; ++i) {
if(!dfn[i])
tarjan(i);
}
bool isok = true;
for(int i = 0; i < 2 * n; i += 2) {
if(color[i] == color[i + 1]) {
isok = false;
break;
}
}
if(!isok) {
printf("bad luck\n");
continue;
}
for(int u = 0; u < 2 * n; ++u) {
for(int i = head[u]; i != -1; i = e[i].nxt) {
int v = e[i].to;
if(color[v] != color[u]){
add_edge2(color[v], color[u]);
in[color[u]] ++;
}
}
opp[color[u]] = color[u^1];
}
for(int i = 0; i < 2 * n; ++i) {
if(!in[i])
topo(i);
}
while(!q.empty()) {
int now = q.front();
q.pop();
if(!ban[now]) {
ban[now] = 1;
ban[opp[now]] = 2;
}
}
int tar = ban[color[0]];
for(int i = 2; i < 2 * n; ++ i) {
if(ban[color[i]] == tar) {
if(i & 1) {
printf("%dh ", i >> 1);
} else {
printf("%dw ", i >> 1);
}
}
}
printf("\n");
}
return 0;
}