Merge remote-tracking branch 'upstream/master'

1 files changed, 36 insertions, 0 deletions

diff --git a/challenge-074/walt-mankowski/cpp/ch-2.cpp b/challenge-074/walt-mankowski/cpp/ch-2.cpp
new file mode 100644
index 0000000000..ab8b330e19
--- /dev/null
+++ b/challenge-074/walt-mankowski/cpp/ch-2.cpp
@@ -0,0 +1,36 @@
+#include <string>
+#include <iostream>
+#include <map>
+#include <list>
+
+using namespace std;
+
+int main(int argc, char *argv[]) {
+    const string s(argv[1]);
+    string out = string(s.length(), ' ');
+    map<char,list<char>::const_iterator> seen;
+    list<char> nr;
+
+    for (size_t i = 0; i < s.length(); i++) {
+        const char c = s[i];
+        
+        // have we seen c before?
+        if (seen.find(c) == seen.end()) {
+            nr.push_front(c);
+            seen[c] = nr.cbegin();
+        } else {
+            // remove c from nr
+            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()) 
+            out[i] = '#';
+        else
+            out[i] = *(nr.cbegin());
+    }
+    cout << out << endl;                
+}