SGU101题解

  1 #include<iostream>
  2 #include<algorithm>
  3 using namespace std;
  4 struct sticktype
  5 {
  6     int l;
  7     int r;
  8     bool vis;
  9 }stick[101];
 10 struct pointtype
 11 {
 12     int amount;
 13     int next[7];
 14     bool vis; 
 15 }point[7];
 16 int tail=0;
 17 int queue[201];
 18 void dfs(int p);
 19 int main()
 20 {
 21     int n;
 22     cin>>n;
 23     for(int i=0;i<=6;i++)
 24     {
 25         point[i].amount=0;
 26         for(int j=0;j<=6;j++)
 27         {
 28             point[i].next[j]=0;
 29         }
 30     }
 31     for(int i=1;i<=n;i++)
 32     {
 33         cin>>stick[i].l>>stick[i].r;
 34         stick[i].vis=false;
 35         point[stick[i].l].vis=false;
 36         point[stick[i].r].vis=false;
 37         point[stick[i].l].amount++;
 38         point[stick[i].l].next[stick[i].r]+=1;
 39         point[stick[i].r].amount++;
 40         point[stick[i].r].next[stick[i].l]+=1;
 41     }
 42     int m=0;
 43     int res=0;
 44     for(int i=0;i<=6;i++)
 45     {
 46         if(point[i].amount!=0)
 47         {
 48             m++;
 49             if(point[i].amount%2!=0)
 50             {
 51                 res++;
 52             }
 53         }
 54     }
 55     if(res!=0&&res!=2)
 56     {
 57         cout<<"No solution";
 58         return 0;
 59     }
 60     int begin;
 61     if(res==0)
 62     {
 63         for(int i=0;i<=6;i++)
 64         {
 65             if(point[i].amount!=0)
 66             {
 67                 begin=i;
 68                 break;
 69             }
 70         }
 71     }
 72     else
 73     {
 74         for(int i=0;i<=6;i++)
 75         {
 76             if(point[i].amount%2!=0)
 77             {
 78                 begin=i;
 79                 break;
 80             }
 81         }
 82     }
 83     dfs(begin);
 84     for(int i=0;i<=6;i++)
 85     {
 86         if(!point[i].vis&&point[i].amount!=0)
 87         {
 88             cout<<"No solution";
 89             return 0;
 90         }
 91     }
 92     for(int i=tail;i>=2;i--)
 93     {
 94         for(int j=1;j<=n;j++)
 95         {
 96             if(!stick[j].vis)
 97             {
 98                 if(stick[j].l==queue[i-1]&&stick[j].r==queue[i])
 99                 {
100                     stick[j].vis=true;
101                     cout<<j<<" -"<<endl;
102                     break;
103                 }
104                 if(stick[j].r==queue[i-1]&&stick[j].l==queue[i])
105                 {
106                     stick[j].vis=true;
107                     cout<<j<<" +"<<endl;
108                     break;
109                 }
110             }    
111         }
112     }
113     return 0;
114 }
115 bool check(int p)
116 {
117     for(int i=0;i<=6;i++)
118     {
119         if(point[p].next[i])
120         {
121             return false;
122         }
123     }
124     return true;
125 }
126 void dfs(int p)
127 {
128     point[p].vis=true;
129     for(int i=0;i<=6;i++)
130     {
131         while(point[p].next[i])
132         {
133             point[p].next[i]--;
134             int next_point=i;
135             point[next_point].next[p]--;
136             dfs(next_point);
137         }
138     }
139     if(check(p))
140     {
141         tail++;
142         queue[tail]=p;
143     }
144     return;
145 }