POJ 2513--colored Sticks "Dictionary tree number && find a link && Euler road"

Colored sticks

Time Limit: 5000MS		Memory Limit: 128000K
Total Submissions: 32351		Accepted: 8536

Description

You are given a bunch of wooden sticks. Each endpoint of all stick is colored with some color. Is it possible to align the sticks in a straight line such that the colors of the endpoints so touch is of the same col Or?

Input

Input is a sequence of lines, each line contains and words, separated by spaces, giving the colors of the endpoints of one Stick. A word is a sequence of lowercase letters no longer than characters. There is no more than 250000 sticks.

Output

If The sticks can is aligned in the desired-line, output a single line saying Possible, otherwise output impossible.

Sample Input

Blue redred Violetcyan blueblue magentamagenta Cyan

Sample Output

Possible

The necessary and sufficient conditions for the existence of the Euler road in the absence of graphs are:

The ① diagram is connected;

② the degree of all nodes is even, or there are only two nodes with an odd degree.

Here are two methods, one is the direct allocation of memory, time:985MS

#include <cstdio> #include <cstring> #include <iostream> #define MAXN 500500using namespace Std;struct    node {int id; Node *next[30];}; Node *root;node TREE[MAXN * 10];//first allocates memory.    int DU[MAXN], PER[MAXN], color;//color number int ans = 0;node *create () {Node *p = &tree[ans++];    for (int i = 0; i <; ++i) P--next[i] = NULL; return p;};    void Insert (char *s, int id) {node *p = root;        for (int i = 0; s[i]; ++i) {int k = s[i]-' a ';        if (P-next[k] = = NULL) P--next[k] = create ();    p = P->next[k]; } P-id = ID;}    int search (char *s) {node *p = root;        for (int i = 0; s[i]; ++i) {int k = s[i]-' a ';        if (P-next[k] = = NULL) return 0;    p = P-next[k]; } return p->id;}    void Init () {for (int i = 1; I <= maxn; ++i) per[i] = i;    memset (Du, 0, sizeof (DU)); color = 0;}    int find (int x) {int r = x; while (r! = Per[r]) R = Per[r];    Per[x] = r; return r;}    void join (int x, int y) {int fx = find (x);    int fy = find (y); PER[FX] = fy;}     BOOL Judge () {int sum = 0;    for (int i = 1; I <= color; ++i) if (du[i]% 2 = = 1) sum++;    if (sum! = 0 && sum! = 2) return false;    int k = find (1);    for (int i = 2; I <= color; ++i) if (k! = Find (i)) return false; return true;}    int main () {char s1[15], s2[15];    Init ();    Root = Create ();        while (CIN >> S1 >> s2) {int x = search (S1);        int y = search (s2);        if (!x) insert (s1,x = ++color);        if (!y) insert (s2,y = ++color);        du[x]++, du[y]++;    Join (x, y);    } if (judge ()) printf ("possible\n");    else printf ("impossible\n"); return 0;}

Second, dynamically allocating memory for a bit longer:1860MS

#include <cstdio> #include <cstring> #include <iostream> #define MAXN 500500using namespace Std;struct Node {int id;//the number of the record color node *next[30];}; Node *root;//node TREE[MAXN * 10];//first allocates memory. int DU[MAXN], per[maxn], color;//int ans = 0;//node *create () {//Node *p = &tree[ans++];//for (int i = 0; I &lt ; 26;    ++i)//P--next[i] = null;//return p;//};void insert (char *s, int id) {node *p = root;        for (int i = 0; s[i]; ++i) {int k = s[i]-' a ';        if (P-next[k] = = NULL) {Node *q = new node;        memset (Q-next,null,sizeof, Q-Next);         P--next[k]= Q;}    p = P->next[k]; } P-id = ID;}    int search (char *s) {node *p = root;        for (int i = 0; s[i]; ++i) {int k = s[i]-' a ';        if (P-next[k] = = NULL) return 0;    p = P-next[k]; } return p->id;}    void Init () {for (int i = 1; I <= maxn; ++i) per[i] = i; memset (Du, 0, sizeof (du)); color = 0;}    void Initroot () {root = new Node;memset (Root-Next, NULL, sizeof (Root->next));} int find (int x) {int r = x;    while (r! = Per[r]) R = Per[r];    Per[x] = r; return r;}    void join (int x, int y) {int fx = find (x);    int fy = find (y); PER[FX] = fy;}     BOOL Judge () {int sum = 0;    for (int i = 1; I <= color; ++i) if (du[i]% 2 = = 1) sum++;    if (sum! = 0 && sum! = 2) return false;    int k = find (1);    for (int i = 2; I <= color; ++i) if (k! = Find (i)) return false; return true;}    int main () {char s1[15], s2[15];    Init ();    Initroot ();    Root = Create ();        while (CIN >> S1 >> s2) {int x = search (S1);        int y = search (s2);        if (!x) insert (s1,x = ++color);        if (!y) insert (s2,y = ++color);        du[x]++, du[y]++;    Join (x, y);    } if (judge ()) printf ("possible\n");    else printf ("impossible\n"); return 0;}

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POJ 2513--colored Sticks "Dictionary tree number && find a link && Euler road"