POJ 1386 Play on Words (to Tuola Road + and collection)

title Link:http://poj.org/problem?id=1386

Thinking Analysis: This question asks whether the word can be connected into a straight line, converted to the graph theory problem: The first letter and the tail letter of the word as a point, each word describes a letter from the beginning of the letter pointing to the edge,

Then all the words make up a direction graph, the question changes to determine whether there is a Euler road in the direction graph; There are two sufficient and necessary conditions for the existence of the Euler road in the direction diagram: The graph is connected and all points are in degrees equal to the degrees of the degree or only two points in the degree and out of the degrees, a point of penetration = out of degrees + 1, the other point into the degree = out of 1;

The code is as follows:

#include <cstdio>#include<cstring>#include<iostream>using namespacestd;Const intMax_n = -;Const intMax_m = ++Ten;intFa[max_n], show[max_n];int inch[Max_n], out[Max_n];intSet_visited[max_n];CharStr[max_m];voidInit () { for(inti =0; i < max_n; ++i) fa[i]=i; memset (inch,0,sizeof(inch)); memset ( out,0,sizeof( out)); Memset (Show,0,sizeof(show)); memset (set_visited,0,sizeof(set_visited));}intFind (inta) {    if(Fa[a] = =a)returnA; Else        returnFa[a] =Find (Fa[a]);}intUnion (intAintb) {    intFa_a =Find (a); intFa_b =Find (b); if(Fa_a = =fa_b)return-1; if(Fa_a >fa_b) Fa[fa_b]=fa_a; ElseFa[fa_a]=Fa_b; return 1;}intMain () {intcase_times, N, Len; scanf ("%d", &case_times);  while(case_times--) {scanf ("%d", &N);        Init ();  for(inti =0; I < n; ++i) {intL, R; scanf ("%s", str); Len=strlen (str); L= str[0] -'a'; R= Str[len-1] -'a'; inch[l]++;  out[r]++; SHOW[L]= Show[r] =1;        Union (l, R); }        intSet_count =0; intNot_equal =0; intIn_big_out =0, out_big_in =0; BOOLOK =true;  for(inti =0; i < max_n; ++i) {if(Show[i]) {intFa_i =Find (i); if(Set_visited[fa_i] = =0) {Set_count++; Set_visited[fa_i]=1; }                if(Set_count >1) {OK=false;  Break; }                if(inch[i]! = out[i]) not_equal++; if(inch[I] = = out[I] +1) In_big_out++; if(inch[I] +1== out[i]) out_big_in++; }        }        if(! (Not_equal = =0) || (out_big_in = =1&& In_big_out = =1&& In_big_out + out_big_in = =not_equal)))  OK=false; if(OK) printf ("Ordering is possible.\n"); Elseprintf ("The door cannot be opened.\n"); }    return 0;}

POJ 1386 Play on Words (to Tuola Road + and collection)