POJ-2513（trie+并查集+欧拉回路）

自认为此题有个bug

#define NUMBER 500005int p[NUMBER + 5];int rank[NUMBER + 5];void make_set(int x) {p[x] = x;rank[x] = 0;}int find_set(int x) {if (x != p[x]) p[x] = find_set(p[x]);return p[x];}void link_set(int x, int y) {if (rank[x] > rank[y]) p[y] = x;else {p[x] = y;if (rank[x] == rank[y]) ++rank[y];}}void union_set(int x, int y){link_set(find_set(x), find_set(y));}int Index;int degree[NUMBER];struct trie{    int cnt;    trie *p[26];} * root;int make_tree(char *s){    trie * r = root;    trie * tmp;    int i, j;    for (i = 0; s[i] != '\0'; ++i) {        if (r->p[s[i] - 'a'] == NULL) {            tmp = new trie;            tmp->cnt = -1;            for (j = 0; j < 26; ++j)                tmp->p[j] = NULL;            r->p[s[i] - 'a'] = tmp;        }        r = r->p[s[i] - 'a'];    }if (r->cnt == -1)r->cnt = Index++;return r->cnt;}int main(){int i, j;root = new trie;    for (i = 0; i < 26; ++i)root->p[i] = NULL;for (i = 0; i < NUMBER; ++i)make_set(i);char a[15], b[15];char s[1000];int flag = 0;while (gets(s) != NULL && flag == 0) {memset(degree, 0, sizeof(degree));for (i = 0; i < NUMBER; ++i)make_set(i);root = new trie; for (i = 0; i < 26; ++i)root->p[i] = NULL;Index = 0;while (strlen(s) != 0 && flag == 0) {sscanf(s, "%s %s", a, b);int x = make_tree(a);int y = make_tree(b);degree[x]++;degree[y]++;union_set(x, y);if (gets(s) == NULL)flag = 1;}int sum = 0;for (i = 0; i < Index; ++i) {if (degree[i] % 2 == 1)++sum;}if (sum == 0 || sum == 2) {int t = find_set(0);for (i = 1; i < Index; ++i) {if (find_set(i) != t) {break;}}if (i >= Index - 1) printf("Possible\n");///////////////////////////buggggggggggggggggggggggggggelse printf("Impossible\n");} else printf("Impossible\n");}return 0;}