CodeForces 358E-Dima and Kicks

CodeForces 358E-Dima and Kicks

Dfs judges the European Union, and the code of the famous player is cool.

First, calculate the sum of the degrees of all vertices. Then, for the particularity of this graph, each vertex can have up to four edges to mark whether the current edge has passed.

If all nodes can be traversed in a DFS, an approximate number set greater than 1 of gcd with all edges is output.

I really learned.

#include #include 
 
  #include 
  
   #include 
   
    #include 
    
     #include 
     
      #include 
      
       #include 
       
        #include 
        #pragma comment(linker, "/STACK:1024000000");#define EPS (1e-8)#define LL long long#define ULL unsigned __int64#define _LL __int64#define INF 0x3f3f3f3f#define Mod 20090717using namespace std;bool vis[1002][1002][4];int num[1010][1010];int dir[2][4] = {{-1,0,1,0},{0,-1,0,1}};int total;int ans;void dfs(int x,int y,int d,int len){ bool mark = false; for(int i = 0;i < 4; ++i) { if(0 == num[x+dir[0][i]][y+dir[1][i]] || vis[x][y][i] == true) continue; vis[x][y][i] = true,vis[x+dir[0][i]][y+dir[1][i]][(i+2)%4] = true; total -= 2; if(d != -1 && i != d) ans = __gcd(ans,len),dfs(x+dir[0][i],y+dir[1][i],i,1); else dfs(x+dir[0][i],y+dir[1][i],i,len+1); mark = true; } if(mark == false) ans = __gcd(ans,len);}int main(){ int n,m,i,j,k; scanf("%d %d",&n,&m); memset(num,0,sizeof(num)); for(i = 1;i <= n; ++i) for(j = 1;j <= m; ++j) scanf("%d",&num[i][j]); int odd = 0; ans = 0; total = 0; for(i = 1;i <= n; ++i) for(j = 1;j <= m; ++j) { if(num[i][j] == 0) continue; for(ans = 0,k = 0;k < 4; ++k) ans += num[i+dir[0][k]][j+dir[1][k]]; total += ans; if(ans == 0) return puts("-1"),0; if(ans&1) odd++; } if(odd != 0 && odd != 2) return puts("-1"),0; memset(vis,false,sizeof(vis)); ans = 0; for(i = 1;i <= n; ++i) for(j = 1;j <= m; ++j) if(num[i][j]) { dfs(i,j,-1,0); goto V; } V:; if(total || ans <= 1) return puts("-1"),0; for(i = 2;i < ans; ++i) if(ans%i == 0) printf("%d ",i); printf("%d\n",ans); return 0;}