Roman_To_Integer.cpp

Programming/C++/Roman_To_Integer/Roman_To_Integer.cpp

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+// Program to convert Roman to numerials
+#include <bits/stdc++.h> 
+using namespace std; 
+
+int romanToInteger(char c)
+{
+  switch(c)
+  {
+    case 'I' : return 1;
+    case 'V' : return 5;
+    case 'X' : return 10;
+    case 'L' : return 50;
+    case 'C' : return 100;
+    case 'D' : return 500;
+    case 'M' : return 1000;
+  }
+  return 0;
+}
+
+int romanToInt(string s) {
+  int size = s.size();
+  if(size==0)
+    return 0;
+  int result = 0;
+  for(int i=1; i<size; i++)
+  {
+    if( romanToInteger(s[i]) > romanToInteger(s[i-1]) )
+      result -= romanToInteger(s[i-1]);
+    else
+      result += (romanToInteger(s[i-1]));
+  }
+  result += romanToInteger(s.back());
+  return result;
+}
+
+// Driver Program 
+int main() 
+{ 
+	// Considering inputs given are valid 
+	string str = "MCMIV"; 
+	cout << "Integer form of Roman Numeral is "
+		<< romanToInt(str) << endl; 
+
+	return 0; 
+}