Determine if it is a Hamiltonian figure--hdu 5424

Test instructions: Give an image without a direction to determine whether it is a Hamiltonian diagram.

Hamilton Road: A pathway that passes through each point and only once.

Method: Each time to find the minimum number of points as a starting point, and then dfs the entire graph, see can traverse to how many points can reach N.

1#include <iostream>2#include <cstdio>3#include <ctime>4#include <cmath>5#include <cstring>6#include <algorithm>7#include <queue>8#include <vector>9#include <climits>Ten#include <Set> One using namespacestd; A Const intmaxn=1100, inf=1E9; -vector<int>G[MAXN]; - intn,vis[maxn],dep,cnt; the BOOLDfsintu) - { -     if(DEP = =N) -         return true; +      for(intI=0; I<g[u].size (); i++) -     { +         intv =G[u][i]; A         if(Vis[v]) at             Continue; -VIS[V] =true; -dep++; -         if(Dfs (v)) -             return true; -DEP-- ; inVIS[V] =0; -     } to     return false; + } - intMain () the { *     intu,v; $      while(SCANF ("%d", &n)! =-1)Panax Notoginseng     { -          for(intI=1; i<=n; i++) the g[i].clear (); +          for(intI=1; i<=n; i++) A         { thescanf"%d%d",&u,&v); + G[u].push_back (v); - g[v].push_back (u); $         } $         intHead=0, cnt=0; -          for(intI=1; i<=n; i++) -             if(g[i].size () = =1) the             { -Head=i;///find a starting pointWuyicnt++; the             } -         if(cnt>2)///If there are more than two points with a degree of 1 Wu         { -Puts"NO"); About             Continue; $         } -memset (Vis,0,sizeof(Vis)); -         if(Head = =0) -Head=1;///no degree is 1, which is a ring Adep=1; +         if(Dfs (head)) thePuts"YES"); -         ElsePuts"NO"); $     } the}

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Determine if it is a Hamiltonian figure--hdu 5424