Update graphs challenges to add connected constraint (donnemartin#151)

Author: donnemartin

graphs_trees/graph/graph_challenge.ipynb

@@ -44,6 +44,8 @@
     "    * Yes\n",
     "* If we try to delete a node that doesn't exist, do we just do nothing?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -278,7 +280,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph/graph_solution.ipynb

@@ -43,6 +43,8 @@
     "    * Yes\n",
     "* If we try to delete a node that doesn't exist, do we just do nothing?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -383,7 +385,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_bfs/bfs_challenge.ipynb

@@ -38,6 +38,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -206,7 +208,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_bfs/bfs_solution.ipynb

@@ -37,6 +37,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -244,7 +246,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_dfs/dfs_challenge.ipynb

@@ -38,6 +38,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -207,7 +209,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_dfs/dfs_solution.ipynb

@@ -37,6 +37,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -229,7 +231,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_path_exists/path_exists_challenge.ipynb

@@ -38,6 +38,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -197,7 +199,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,

graphs_trees/graph_path_exists/path_exists_solution.ipynb

@@ -37,6 +37,8 @@
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
     "    * Yes\n",
+    "* Can we assume this is a connected graph?\n",
+    "    * Yes\n",
     "* Can we assume the inputs are valid?\n",
     "    * Yes\n",
     "* Can we assume this fits memory?\n",
@@ -240,7 +242,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.0"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,