【拓扑排序】 HDOJ 1811 Rank of Tetris

#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 10005
#define maxm 20005
#define eps 1e-10
#define mod 998244353
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
// head

int h[maxn], next[maxm], v[maxm];
int H[maxn], NEXT[maxm], V[maxm];
int f[maxn], in[maxn], id[maxn];
char s[100];
queue<int> q;
int cnt, n, m, CNT;

int find(int x)
{
return x == f[x] ? f[x] : f[x] = find(f[x]);
}
void init(void)
{
cnt = CNT = 0;
memset(in, 0, sizeof in);
memset(h, -1, sizeof h);
memset(H, -1, sizeof H);
for(int i = 0; i <= n; i++) f[i] = i;
}
void addedges(int u, int vv)
{
next[cnt] = h[u], h[u] = cnt, v[cnt] = vv, cnt++;
}
void Addedges(int u, int vv)
{
NEXT[CNT] = H[u], H[u] = CNT, V[CNT] = vv, CNT++;
}
void narrow(void)
{
m = 0;
for(int i = 0; i < n; i++) if(find(i) == i) id[f[i]] = ++m;
for(int i = 0; i < n; i++)
for(int e = H[i]; ~e; e = NEXT[e])
addedges(id[f[i]], id[f[V[e]]]), in[id[f[V[e]]]]++;
}
void debug(void)
{
for(int i = 1; i <= m; i++) {
printf("%d :: ", i);
for(int e = h[i]; ~e; e = next[e])
printf("%d ", v[e]);
printf("\n");
}
}
void work(void)
{
int ok = 1, a, b, aa, bb, inq, num;
while(m--) {
scanf("%d%s%d", &a, s, &b);
aa = find(a), bb = find(b);
if(s[0] == '=') {
if(aa > bb) f[aa] = bb;
else f[bb] = aa;
}
if(aa == bb && s[0] != '=') ok = 0;
if(s[0] == '>') Addedges(b, a);
if(s[0] == '<') Addedges(a, b);
}
if(!ok) {
printf("CONFLICT\n");
return;
}
narrow();
inq = num = 0;
for(int i = 1; i <= m; i++)
if(!in[i]) {
q.push(i);
inq++, num++;
if(inq > 1) ok = 0;
}
while(!q.empty()) {
int u= q.front(); q.pop(), inq--;
for(int e = h[u]; ~e; e = next[e]) {
in[v[e]]--;
if(!in[v[e]]) {
q.push(v[e]);
inq++, num++;
if(inq > 1) ok = 0;
}
}
}
if(num < m) printf("CONFLICT\n");
else if(!ok) printf("UNCERTAIN\n");
else printf("OK\n");
}
int main(void)
{
while(scanf("%d%d", &n, &m)!=EOF) {
init();
work();
}
return 0;
}