add solution for lab07

.vscode/launch.json

@@ -104,6 +104,20 @@
             "MIMode": "gdb",
             "miDebuggerPath": "/usr/bin/gdb",
             "preLaunchTask": "C/C++: g++ build active file"
+        },
+        {
+            "name": "lab07",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "${fileDirname}/${fileBasenameNoExtension}",
+            "args": [
+                "input.txt"
+            ],
+            "cwd": "${fileDirname}",
+            "environment": [],
+            "MIMode": "gdb",
+            "miDebuggerPath": "/usr/bin/gdb",
+            "preLaunchTask": "C/C++: g++ build single active file"
         }
     ]
 }

labs/maps/checkpoint1.cpp

@@ -0,0 +1,43 @@
+#include <iostream>
+#include <fstream>
+#include <map>
+using namespace std;
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        cerr << "Usage: " << argv[0] << " inputfile" << endl;
+        return 1;
+    }
+
+    ifstream fin(argv[1]);
+    if (!fin) {
+        cerr << "Error opening file " << argv[1] << endl;
+        return 1;
+    }
+
+    // Use operator[] to count frequency of each integer.
+    map<int, int> counts;
+    int number;
+    while (fin >> number) {
+        counts[number] = counts[number] + 1;
+    }
+
+    // Find the maximum frequency.
+    int maxCount = 0;
+    for (map<int, int>::iterator it = counts.begin(); it != counts.end(); ++it) {
+        if (it->second > maxCount) {
+            maxCount = it->second;
+        }
+    }
+
+    // Print all numbers with frequency equal to maxCount.
+    cout << "Modes: ";
+    for (map<int, int>::iterator it = counts.begin(); it != counts.end(); ++it) {
+        if (it->second == maxCount) {
+            cout << it->first << " ";
+        }
+    }
+    cout << endl;
+
+    return 0;
+}

labs/maps/checkpoint2.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <fstream>
+#include <map>
+using namespace std;
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        cerr << "Usage: " << argv[0] << " inputfile" << endl;
+        return 1;
+    }
+
+    ifstream fin(argv[1]);
+    if (!fin) {
+        cerr << "Error opening file " << argv[1] << endl;
+        return 1;
+    }
+
+    // Map to count frequencies; using find/insert instead of operator[].
+    map<int, int> counts;
+    int number;
+    while (fin >> number) {
+        map<int, int>::iterator it = counts.find(number);
+        if (it != counts.end()) {
+            it->second = it->second + 1;
+        } else {
+            counts.insert(pair<int, int>(number, 1));
+        }
+    }
+
+    // Find the maximum frequency.
+    int maxCount = 0;
+    for (map<int, int>::iterator it = counts.begin(); it != counts.end(); ++it) {
+        if (it->second > maxCount) {
+            maxCount = it->second;
+        }
+    }
+
+    // Print all numbers with frequency equal to maxCount.
+    cout << "Modes: ";
+    for (map<int, int>::iterator it = counts.begin(); it != counts.end(); ++it) {
+        if (it->second == maxCount) {
+            cout << it->first << " ";
+        }
+    }
+    cout << endl;
+
+    return 0;
+}

labs/maps/input.txt

@@ -0,0 +1 @@
+19 83 -12 83 65 19 45 -12 45 19 45

labs/maps/phonebook2.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <map>
+#include <string>
+using namespace std;
+
+// Add a number, name pair to the phonebook using a map.
+void add(map<int, string>& phonebook, int number, const string &name) {
+    map<int, string>::iterator it = phonebook.find(number);
+    if (it != phonebook.end()) {
+        it->second = name;
+    } else {
+        phonebook.insert(pair<int, string>(number, name));
+    }
+}
+
+// Given a phone number, determine who is calling.
+void identify(const map<int, string>& phonebook, int number) {
+    map<int, string>::const_iterator it = phonebook.find(number);
+    if (it == phonebook.end())
+        cout << "unknown caller!" << endl;
+    else
+        cout << it->second << " is calling!" << endl;
+}
+
+int main() {
+    // Init
+    map<int, string> phonebook;
+
+    // Add
+    add(phonebook, 1111, "fred");
+    add(phonebook, 2222, "sally");
+    add(phonebook, 3333, "george");
+    add(phonebook, 1234567, "alice");
+    add(phonebook, 7654321, "bob");
+
+    // Test
+    identify(phonebook, 2222);
+    identify(phonebook, 4444);
+    identify(phonebook, 1234567);
+    
+    return 0;
+}