1 #include<stdio.h> 2 #include<string.h> 3 #define doumax(a,b) (a>b?a:b) 4 const int maxn=100; 5 int mat[maxn][maxn],dp[maxn],n; 6 struct node{ 7     int a; 8     int b; 9     void dousort(void)10     {11         if(a<b){12             int temp=a;13             a=b;14             b=temp;15         }16     }17     bool operator<(const node & t)18     {19         return t.a>a && t.b>b;20     }21     void operator=(const node & t)22     {23         a=t.a;b=t.b;24     }25 }rect[maxn],rectinit[maxn];26 int dpmodel(int i);27 void print_road(int i);28 int main()29 {30     while(scanf("%d",&n)==1){31         for(int i=1;i<=n;i++){32             scanf("%d%d",&rect[i].a,&rect[i].b);33             rectinit[i]=rect[i];34             rect[i].dousort();35         }36         memset(mat,0,sizeof(mat));37         memset(dp,0,sizeof(dp));38         for(int i=1;i<=n;i++)39             for(int j=i+1;j<=n;j++){40                 if(rect[i]<rect[j])41                     mat[i][j]=1;42                 else if(rect[j]<rect[i])43                     mat[j][i]=1;44             }45         int maxroad=0,maxi;46         for(int i=1;i<=n;i++){47             if(maxroad<dpmodel(i)){48                  maxroad=dpmodel(i);49                  maxi=i;50             }51         }52         printf("%d\n",maxroad);53         print_road(maxi);54     }55     return 0;56 }57 int dpmodel(int i)58 {59     if(dp[i]>0)60         return dp[i];61     dp[i]=1;62     for(int j=1;j<=n;j++)63         if(mat[i][j])64         dp[i]=doumax(dp[i],dpmodel(j)+1);65     return dp[i];66 }67 void print_road(int i)68 {69     printf("(%d,%d)\n",rectinit[i].a,rectinit[i].b);70     if(dp[i]==1)71         return;72     for(int j=1;j<=n;j++)73     if(mat[i][j] && dp[i]==dp[j]+1){74         print_road(j);75         return;76     }77 }