From d76d3b42ff9750f5460f729e32b181e4c0cbc06d Mon Sep 17 00:00:00 2001
From: Peter Norvig <peter@norvig.com>
Date: Tue, 12 Dec 2017 14:49:56 -0500
Subject: [PATCH] Advent 2017 through Day 12

---
 ipynb/Advent 2017.ipynb | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/ipynb/Advent 2017.ipynb b/ipynb/Advent 2017.ipynb
index 2fba0e1..d6f964c 100644
--- a/ipynb/Advent 2017.ipynb	
+++ b/ipynb/Advent 2017.ipynb	
@@ -1917,7 +1917,7 @@
     "\n",
     "# [Day 12](https://adventofcode.com/2017/day/12): Digital Plumber\n",
     "\n",
-    "First I'll parse the data, creating a dict of `{program: direct_group_of_proggrams}`:"
+    "First I'll parse the data, creating a dict of `{program: direct_group_of_programs}`:"
    ]
   },
   {
@@ -2004,12 +2004,12 @@
     "\n",
     "**Part Two**\n",
     "\n",
-    "I did almost all the work; I just need to count the unique groups. The minimum value in a group uniquely identifies it, so:"
+    "I did almost all the work; I just need to count the number of distinct groups. That's a set of sets, so I have to use my `Set` class (because regular `set`s are not hashable):"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 53,
+   "execution_count": 56,
    "metadata": {
     "collapsed": false
    },
@@ -2020,13 +2020,13 @@
        "221"
       ]
      },
-     "execution_count": 53,
+     "execution_count": 56,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
-    "len({min(G[i]) for i in G})"
+    "len({Set(G[i]) for i in G})"
    ]
   }
  ],