http://acm.hdu.edu.cn/showproblem.php?pid=1814
输出最小字典序。
1 #include<bits/stdc++.h> 2 const int MAXN = 20020; 3 const int MAXM = 100010; 4 using namespace std; 5 struct Edge { 6 int to,next; 7 }edge[MAXM]; 8 int head[MAXN],tot; 9 void init(){ 10 tot = 0; 11 memset(head,-1,sizeof(head)); 12 } 13 void addedge(int u,int v){ 14 edge[tot].to = v; 15 edge[tot].next = head[u]; 16 head[u] = tot++; 17 } bool vis[MAXN];//è¾é«±ê¼Ç￡¬Îatrue±íê¾Ñ¡Ôñ 18 int S[MAXN],top;//Õ» 19 bool dfs(int u){ 20 if(vis[u^1])return false; 21 if(vis[u])return true; 22 vis[u] = true; 23 S[top++] = u; 24 for(int i = head[u];i != -1;i = edge[i].next) 25 if(!dfs(edge[i].to)) 26 return false; 27 return true; 28 } 29 bool Twosat(int n){ 30 memset(vis,false,sizeof(vis)); 31 for(int i = 0;i < n;i += 2){ 32 if(vis[i] || vis[i^1]) 33 continue; 34 top = 0; 35 if(!dfs(i)){ 36 while(top) 37 vis[S[--top]] = false; 38 if(!dfs(i^1)) return false; 39 } 40 } 41 return true; 42 } 43 int main(){ 44 int n,m; 45 int u,v; 46 while(scanf("%d%d",&n,&m) == 2){ 47 init(); 48 while(m--){ 49 scanf("%d%d",&u,&v); 50 u--;v--; 51 addedge(u,v^1); 52 addedge(v,u^1); 53 } 54 if(Twosat(2*n)){ 55 for(int i = 0;i < 2*n;i++) 56 if(vis[i]) 57 printf("%d ",i+1); 58 } 59 else printf("NIE "); 60 } 61 return 0; 62 }