hdu1814 Peaceful Commission

hdu1814 Peaceful Commission

题意：2-sat裸题，打印字典序最小的

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我写了三个

1. 染色做法，正解
2. scc做法，不管字典序
3. scc做法，错误的字典序贪心

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 2e4+5, M = 1e5+5;

inline int read() {
	int x = 0, f = 1; char c = getchar();
	while(c<'0' || c>'9') {if(c=='-') f=-1; c=getchar();}
	while(c>='0' && c<='9') {x=x*10+c-'0'; c=getchar();}
	return x * f;
}

int n, m;
struct edge {int v, ne;} e[M];
int cnt, h[N];
inline void ins(int u, int v) {
	e[++cnt] = (edge) {v, h[u]}; h[u] = cnt;
}
inline int id(int x) {return ((x-1)^1)+1;}
int col[N], st[N], top;
bool dfs(int u) {
	if(col[u]) return true;
	if(col[id(u)]) return false;
	col[u] = 1; st[top++] = u;
	for(int i=h[u]; i; i=e[i].ne) {
		int v = e[i].v;
		if(!dfs(v)) return false;
	}
	return true;
}
bool check(int u) {
	top = 1;
	return dfs(u);
}
int main() {
	freopen("in", "r", stdin);
	while(cin >> n) {
		cnt = 0;
		memset(h, 0, sizeof(h));
		memset(col, 0, sizeof(col));
		m = read();
		for(int i=1; i<=m; i++) {
			int a = read(), b = read();
			ins(a, id(b));
			ins(b, id(a));
		}
		int flag =  0;
		for(int i=1; i<=n<<1; i+=2) if(!col[i] && !col[id(i)]) {
			if(!check(i)) {
				while(top) col[ st[top--] ] = 0;
				//for(int i=1; i<=n; i++) printf("col %d %d\n", i, col[i]);
				if(!check(id(i))) {
					puts("NIE"), flag = 1;
					break;
				}
			}
		}
		if(flag) continue;
		for(int i=1; i<=n<<1; i+=2) {
			if(col[i]) printf("%d\n", i);
			else printf("%d\n", i+1);
		}
	}
}

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 2e4+5, M = 1e5+5;

inline int read() {
	int x = 0, f = 1; char c = getchar();
	while(c<'0' || c>'9') {if(c=='-') f=-1; c=getchar();}
	while(c>='0' && c<='9') {x=x*10+c-'0'; c=getchar();}
	return x * f;
}

int n, m;
struct edge {int v, ne;} e[M];
int cnt, h[N];
inline void ins(int u, int v) {
	e[++cnt] = (edge) {v, h[u]}; h[u] = cnt;
}
int dfn[N], dfc, scc, belong[N], low[N];
int st[N], top;
void dfs(int u) {
	dfn[u] = low[u] = ++dfc;
	st[++top] = u;
	for(int i=h[u]; i; i=e[i].ne) {
		int v = e[i].v;
		if(!dfn[v]) {
			dfs(v);
			low[u] = min(low[u], low[v]);
		} else if(!belong[v]) low[u] = min(low[u], dfn[v]);
	}
	if(dfn[u] == low[u]) {
		scc++;
		while(true) {
			int x = st[top--];
			belong[x] = scc;
			if(x == u) break;
		}
	}
}
namespace G {
	edge e[M];
	int cnt, h[N], ind[N];
	inline void ins(int u, int v) {
		e[++cnt] = (edge) {v, h[u]}; h[u] = cnt;
		ind[v] ++;
	}
	int q[N], head = 1, tail = 1;
#define pii pair<int, int>
#define fir first
#define sec second
	//priority_queue<pii, vector<pii>, greater<pii> > q;
	int col[N], opp[N];
	void dfs_color(int u) {
		if(col[u]) return;
		col[u] = -1;
		for(int i=h[u]; i; i=e[i].ne) dfs_color(e[i].v);
	}
	bool check() {
		for(int i=1; i<=n; i++) if(belong[i] == belong[i+n]) return false;
		return true;
	}
	void topo_sort() {
		head = tail = 1;
		for(int i=1; i<=scc; i++) if(!ind[i]) q[tail++] = i;
		while(head != tail) {
			int u = q[head++]; printf("uuu %d %d\n", u, col[u]);
			if(col[u]) continue;
			col[u] = 1;
			dfs_color(opp[u]);
			for(int i=h[u]; i; i=e[i].ne) {
				int v = e[i].v;
				ind[v] --;
				if(ind[v] == 0) q[tail++] = v;
			}
		}
	}
}
int main() {
	freopen("in", "r", stdin);
	while(cin >> n) {
		m = read();
		for(int i=1; i<=m; i++) {
			int a = read(), b = read();
			ins(a, b+n);
			ins(b, a+n);
		}
		for(int i=1; i<=n<<1; i++) if(!dfn[i]) dfs(i);
		if(!G::check()) {
			puts("NIE");
			continue;
		}
		for(int u=1; u<=n<<1; u++) {
			int a = belong[u];
			for(int i=h[u]; i; i=e[i].ne) {
				int b = belong[e[i].v];
				if(a != b) ins(b, a);
			}
		}
		for(int i=1; i<=n; i++) {
			int a = belong[2*i-1], b = belong[2*i];
			G::opp[a] = b;
			G::opp[b] = a;
			printf("hi %d   %d %d\n", i, belong[a], belong[b]);
		}
		G::topo_sort();
		for(int i=1; i<=n<<1; i++)
			if(G::col[belong[i]] == 1) printf("%d\n", i);
	}
}

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 2e4+5, M = 1e5+5;

inline int read() {
	int x = 0, f = 1; char c = getchar();
	while(c<'0' || c>'9') {if(c=='-') f=-1; c=getchar();}
	while(c>='0' && c<='9') {x=x*10+c-'0'; c=getchar();}
	return x * f;
}

int n, m;
struct edge {int v, ne;} e[M];
int cnt, h[N];
inline void ins(int u, int v) {
	e[++cnt] = (edge) {v, h[u]}; h[u] = cnt;
}
int dfn[N], dfc, scc, belong[N], low[N];
int st[N], top;
void dfs(int u) { //printf("dfs %d\n", u);
	dfn[u] = low[u] = ++dfc;
	st[++top] = u;
	for(int i=h[u]; i; i=e[i].ne) {
		int v = e[i].v;
		if(!dfn[v]) {
			dfs(v);
			low[u] = min(low[u], low[v]);
		} else if(!belong[v])
			low[u] = min(low[u], dfn[v]);
	}
	if(dfn[u] == low[u]) {
		scc++;
		while(true) {
			int x = st[top--];
			belong[x] = scc;
			if(x == u) break;
		}
	}
}
inline int id(int x) {
	int t = ((x-1) >> 1) + 1;
	if(x == t<<1) return x-1;
	else return x+1;
}
int mn[N];
namespace G {
	edge e[M];
	int cnt, h[N], ind[N];
	inline void ins(int u, int v) {
		e[++cnt] = (edge) {v, h[u]}; h[u] = cnt;
		ind[v] ++;
	}
	//int q[N], head = 1, tail = 1;
#define pii pair<int, int>
#define fir first
#define sec second
	priority_queue<pii, vector<pii>, greater<pii> > q;
	int col[N], opp[N];
	void dfs_color(int u) {
		if(col[u]) return;
		col[u] = -1;
		for(int i=h[u]; i; i=e[i].ne) dfs_color(e[i].v);
	}
	bool check() {
		for(int i=1; i<=n; i++) if(belong[(i<<1)-1] == belong[i<<1]) return false;
		return true;
	}
	void topo_sort() {
		for(int i=1; i<=scc; i++) if(!ind[i]) q.push(make_pair(mn[i], i));
		while(!q.empty()) {
			int u = q.top().sec; q.pop(); printf("uuu %d  %d\n", u, mn[u]);
			if(col[u]) continue;
			col[u] = 1;
			dfs_color(opp[u]);
			for(int i=h[u]; i; i=e[i].ne) {
				int v = e[i].v;
				ind[v] --;
				if(ind[v] == 0) q.push(make_pair(mn[v], v));
			}
		}
	}
}
int main() {
	freopen("in", "r", stdin);
	while(cin >> n) {
		memset(dfn, 0, sizeof(dfn));
		memset(low, 0, sizeof(low));
		memset(belong, 0, sizeof(belong));

		dfc = scc = 0;
		cnt = 0; G::cnt = 0;
		memset(h, 0, sizeof(h));
		memset(G::h, 0, sizeof(G::h));
		memset(G::col, 0, sizeof(G::col));
		memset(G::ind, 0, sizeof(G::ind));
		memset(mn, 0x3f, sizeof(mn));

		m = read();
		for(int i=1; i<=m; i++) {
			int a = read(), b = read();
			ins(a, id(b));
			ins(b, id(a));
			//printf("id %d %d\n", id(a), id(b));
		}
		for(int i=1; i<=n<<1; i++) if(!dfn[i]) dfs(i);
		if(!G::check()) {
			puts("NIE");
			continue;
		}
		for(int u=1; u<=n<<1; u++) {
			int a = belong[u];
			mn[a] = min(mn[a], u);
			for(int i=h[u]; i; i=e[i].ne) {
				int b = belong[e[i].v];
				if(a != b) G::ins(b, a);
			}
		}
		//for(int i=1; i<=n<<1; i++) printf("belong %d %d  %d\n", i, belong[i], mn[belong[i]]);
		for(int i=1; i<=n; i++) {
			int a = belong[(i<<1)-1], b = belong[i<<1];
			G::opp[a] = b;
			G::opp[b] = a;
			//printf("hi %d   %d %d\n", i, belong[a], belong[b]);
		}
		G::topo_sort();
		//for(int i=1; i<=n<<1; i++) printf("col %d %d  %d\n", i, belong[i], G::col[i]);
		for(int i=1; i<=n<<1; i+=2) {
			if(G::col[belong[i]] == 1) printf("%d\n", i);
			else printf("%d\n", id(i));
		}
	}
}