DFS
万事开头难，哈哈，现在好爱DFS，通俗易懂~~
var findCircleNum = function(M) { let n=M.length; if(n==0) return 0; let circle=0; let visited=[...Array(n)].map(_=>false); for(var i=0;i<n;i++){ if(!visited[i]){ dfs(M,visited,i); circle++; } } return circle; function dfs(M,visited,i){ visited[i]=true; for(var k=0;k<n;k++){ if(M[i][k]==1&&!visited[k]) dfs(M,visited,k); } } };
