标签：blog io color ar sp for on 2014 问题
/*
2sat问题
输出任意一组可行解
*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
#include<queue>
#include<vector>
using namespace std;
#define N 2100
struct node {
int u,v,next;
}ff[N],bian[N*N*8];
int head[N],yong,low[N],dfn[N],belong[N],ans,top,index,stac[N],vis[N];
void init()
{
memset(head,-1,sizeof(head));
yong=index=ans=top=0;
memset(vis,0,sizeof(vis));
memset(dfn,0,sizeof(dfn));
}
void addedge(int u,int v)
{
bian[yong].u=u;//有的时候不能少,因为下面要用到
bian[yong].v=v;
bian[yong].next=head[u];
head[u]=yong++;
}
void tarjan(int u)
{
low[u]=dfn[u]=++index;
stac[++top]=u;
vis[u]=1;
int i;
for(i=head[u]; i!=-1; i=bian[i].next)
{
int v=bian[i].v;
if(!dfn[v])
{
tarjan(v);
low[u]=min(low[u],low[v]);
}
else if(vis[v])
low[u]=min(low[u],dfn[v]);
}
if(low[u]==dfn[u])
{
ans++;
int t;
do
{
t=stac[top--];
belong[t]=ans;
vis[t]=0;
}
while(t!=u);
}
}
int slove(int n)
{
int i;
for(i=0; i<n*2; i++)
if(!dfn[i])
tarjan(i);
// printf("%d\n",ans);
for(i=0; i<n; i++)
if(belong[i]==belong[i+n])
return 0;
return 1;
}
int judge(struct node a,struct node b) {
if(a.v<=b.u||b.v<=a.u)
return 0;
return 1;
}
int fp[N],indegree[N],color[N];
vector<int>q[N];
void print(struct node a) {
printf("%02d:%02d %02d:%02d\n",a.u/60,a.u%60,a.v/60,a.v%60);
}
void oper(int n) {
int i;
for(i=0;i<n;i++) {
fp[belong[i]]=belong[i+n];
fp[belong[i+n]]=belong[i];
}
for(i=1;i<=ans;i++) {
q[i].clear();
color[i]=0;
indegree[i]=0;
}
for(i=0;i<yong;i++) {
int aa=bian[i].u;
int bb=bian[i].v;
if(belong[aa]!=belong[bb]) {
q[belong[bb]].push_back(belong[aa]);
indegree[belong[aa]]++;
}
}
queue<int>qq;
for(i=1;i<=ans;i++) {
if(indegree[i]==0)
qq.push(i);
}
while(!qq.empty()) {
int cur=qq.front();
qq.pop();
if(color[cur]==0) {
color[cur]=1;
color[fp[cur]]=2;
}
for(i=0;i<(int)q[cur].size();i++) {
int v=q[cur][i];
if(--indegree[v]==0)
qq.push(v);
}
}
for(i=0;i<n;i++) {
if(color[belong[i]]==1)
print(ff[i]);
else
print(ff[i+n]);
}
}
int main() {
int n,i,j,k,u,v,uu,vv,d;
while(scanf("%d",&n)!=EOF) {
for(i=0;i<n;i++) {
scanf("%d:%d %d:%d%d",&u,&v,&uu,&vv,&d);
j=u*60+v;
k=uu*60+vv;
ff[i].u=j;ff[i].v=j+d;
ff[i+n].u=k-d;ff[i+n].v=k;
}
init();
for(i=0;i<n-1;i++)
for(j=i+1;j<n;j++) {
if(judge(ff[i],ff[j])) {
addedge(i,j+n);
addedge(j,i+n);
}
if(judge(ff[i],ff[j+n])) {
addedge(i,j);
addedge(j+n,i+n);
}
if(judge(ff[i+n],ff[j])) {
addedge(i+n,j+n);
addedge(j,i);
}
if(judge(ff[i+n],ff[j+n])) {
addedge(i+n,j);
addedge(j+n,i);
}
}
if(!slove(n)) {
printf("NO\n");
continue;
}
printf("YES\n");
oper(n);
}
return 0;}
标签：blog io color ar sp for on 2014 问题
原文地址：http://blog.csdn.net/u011483306/article/details/40978907
