From 13cdfa88e53569f70d9094b2d858490224a6cb25 Mon Sep 17 00:00:00 2001
From: Walt Mankowski <waltman@pobox.com>
Date: Thu, 20 Aug 2020 20:53:47 -0400
Subject: check for double-delete when removing c from nr

After it's been removed, set the value in seen to end() so we know not
to erase it again.
---
 challenge-074/walt-mankowski/cpp/ch-2.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'challenge-074/walt-mankowski/cpp/ch-2.cpp')

diff --git a/challenge-074/walt-mankowski/cpp/ch-2.cpp b/challenge-074/walt-mankowski/cpp/ch-2.cpp
index 01fb9a916b..b5f32cc7a4 100644
--- a/challenge-074/walt-mankowski/cpp/ch-2.cpp
+++ b/challenge-074/walt-mankowski/cpp/ch-2.cpp
@@ -20,9 +20,13 @@ int main(int argc, char *argv[]) {
         if (seen.find(c) == seen.end()) {
             nr.push_front(c);
             seen[c] = nr.cbegin();
-        } else
+        } else {
             // remove c from nr
-            nr.erase(seen[c]);
+            if (seen[c] != nr.end()) {
+                nr.erase(seen[c]);
+                seen[c] = nr.end();
+            }
+        }
 
         // now the FNR is either the last element of nr, or #
         if (nr.empty()) 
-- 
cgit