poj 2513Colored Sticks
http://poj.org/problem?id=2513
1 #include<cstdio> 2 #include<cstdlib> 3 #include<cstring> 4 using namespace std; 5 6 const int sign_node=26; 7 const int max_node=550000; 8 int f[max_node]; 9 int du[max_node]; 10 int num=0; 11 int ch[max_node][sign_node]; 12 int val[max_node]; 13 14 struct Trie 15 { 16 int sz; 17 void clear(){sz=1; memset(ch[0],0,sizeof(ch[0]));} 18 int idx(char c) {return c-'a';} 19 20 int insert(char *s) 21 { 22 int u=0,n=strlen(s); 23 for(int i=0; i<n; i++){ 24 int c=idx(s[i]); 25 if(!ch[u][c]){ 26 memset(ch[sz],0,sizeof(ch[sz])); 27 val[sz]=0; 28 ch[u][c]=sz++; 29 } 30 u=ch[u][c]; 31 } 32 if(!val[u]) val[u]=++num; 33 return val[u]; 34 } 35 }; 36 37 int find(int x) 38 { 39 if(x!=f[x]) 40 f[x]=find(f[x]); 41 return f[x]; 42 } 43 44 void merge(int x,int y) 45 { 46 int fx=find(x); 47 int fy=find(y); 48 if(fx!=fy){ 49 f[fx]=fy; 50 } 51 } 52 53 void inti() 54 { 55 memset(du,0,sizeof(du)); 56 for(int i=0; i<=max_node; i++) 57 f[i]=i; 58 } 59 60 int main() 61 { 62 Trie trie; 63 char a[100],b[100]; 64 inti(); 65 trie.clear(); 66 while(scanf("%s%s",a,b)!=EOF) 67 { 68 int id1=trie.insert(a); 69 int id2=trie.insert(b); 70 du[id1]++; 71 du[id2]++; 72 merge(id1,id2); 73 } 74 int ans=0,ans1=0; 75 for(int i=1; i<=num; i++) 76 { 77 if(du[i]&1) 78 ans++; 79 if(ans>2||find(1)!=find(i)) 80 { 81 printf("Impossible\n"); 82 return 0; 83 } 84 } 85 if(ans==1) 86 printf("Impossible\n"); 87 else 88 printf("Possible\n"); 89 return 0; 90 }
