added solution for sacramento crime report

VL03-04-01/main.cc

@@ -0,0 +1,149 @@
+#include <iostream>
+#include <vector>
+#include <fstream>
+#include <map>
+
+typedef struct CrimeReportRow {
+  std::string address;
+  std::string district;
+  std::string crime;
+} CrimeReportRow;
+
+class CrimeReport {
+  private:
+    std::vector<CrimeReportRow*> rows;
+
+    std::vector<std::string> split(const std::string& line, const std::string delimiter = ",") {
+      std::vector<std::string> columns;
+      std::string column;
+      int last = 0;
+      int next = 0;
+
+      while ((next = line.find(delimiter, last)) != std::string::npos) {
+        columns.push_back(line.substr(last, next - last));
+        last = next + 1;
+      }
+
+      columns.push_back(line.substr(last));
+      return columns;
+    }
+
+    void read_rows(std::string filename) {
+      std::ifstream file(filename);
+      std::string line;
+      int rownumber = 0;
+
+      if (file.is_open()) {
+        while (std::getline(file, line)) {
+          rownumber++;
+
+          // skip the first line of the file because it is the heading.
+          if (rownumber == 1) {
+            continue;
+          }
+
+          std::vector<std::string> columns = split(line);
+
+          // skip rows with an unexpected amount of columns.
+          if (columns.size() != 9) {
+            std::cout << "Line " << rownumber << " is not valid!" << std::endl;
+          }
+
+          CrimeReportRow* row = new CrimeReportRow;
+          row->district = columns[2];
+          row->address = columns[1];
+          row->crime = columns[5];
+          rows.push_back(row);
+        }
+
+        file.close();
+      }
+    }
+
+  public:
+    CrimeReport(std::string filename) {
+      read_rows(filename);
+    }
+
+    ~CrimeReport() {
+      for (CrimeReportRow* row : rows) {
+        delete row;
+      }
+      
+      rows.clear();
+      rows.shrink_to_fit();
+    }
+
+    int get_number_of_crimes() {
+      return rows.size();
+    }
+
+    std::string get_most_frequent_crime() {
+      std::map<std::string, int> crimes;
+
+      for (CrimeReportRow* row : rows) {
+        crimes[row->crime] += 1;
+      }
+
+      std::pair<std::string, int> crime;
+
+      for (std::map<std::string, int>::iterator it = crimes.begin(); it != crimes.end(); it++) {
+        if (it->second > crime.second) {
+          crime = std::make_pair(it->first, it->second);
+        }
+      }
+
+      return crime.first;
+    }
+
+    std::string get_most_dangerous_district() {
+      std::map<std::string, int> districts;
+
+      for (CrimeReportRow* row : rows) {
+        districts[row->district] += 1;
+      }
+
+      std::pair<std::string, int> district;
+
+      for (std::map<std::string, int>::iterator it = districts.begin(); it != districts.end(); it++) {
+        if (it->second > district.second) {
+          district = std::make_pair(it->first, it->second);
+        }
+      }
+
+      return district.first;
+    }
+
+    std::vector<std::string> get_list_of_address_with_multiple_crimes() {
+      std::map<std::string, int> addresses;
+
+      for (CrimeReportRow* row : rows) {
+        addresses[row->address] += 1;
+      }
+
+      std::vector<std::string> addresses_crimes;
+
+      for (std::map<std::string, int>::iterator it = addresses.begin(); it != addresses.end(); it++) {
+        if (it->second > 1) {
+          addresses_crimes.push_back(it->first);
+        }
+      }
+
+      return addresses_crimes;
+    }
+};
+
+int main() {
+  CrimeReport* report = new CrimeReport("input.csv");
+  std::cout << "Anzahl der Verbrechen: " << report->get_number_of_crimes() << std::endl;
+  std::cout << "Häufigstes Verbrechen: " << report->get_most_frequent_crime() << std::endl;
+  std::cout << "Gefährlichster District: " << report->get_most_dangerous_district() << std::endl;
+  
+  std::cout << "Adresse mit mehr als einem Verbrechen: " << std::endl;
+
+  for (std::string address : report->get_list_of_address_with_multiple_crimes()) {
+    std::cout << "\t" << address << std::endl;
+  }
+
+  return 0;
+}