Implement roman-to-integer

name: roman-to-integer
url: https://leetcode.com/problems/roman-to-integer
difficulty: easy

time: 4ms
time-rank: 92.61%
time-complexity: O(N)

space: 6.3MB
space-rank: 80.43%
space-complexity: O(1)

Fixes #226

Signed-off-by: Christopher Friedt <[email protected]>

Author: cfriedt

roman-to-integer-test.cpp

@@ -0,0 +1,37 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <gtest/gtest.h>
+
+#include "roman-to-integer.cpp"
+
+TEST(RomanToInteger, II) { EXPECT_EQ(2, Solution().romanToInt("II")); }
+TEST(RomanToInteger, XII) { EXPECT_EQ(12, Solution().romanToInt("XII")); }
+TEST(RomanToInteger, XXVII) { EXPECT_EQ(27, Solution().romanToInt("XXVII")); }
+TEST(RomanToInteger, IV) { EXPECT_EQ(4, Solution().romanToInt("IV")); }
+TEST(RomanToInteger, IX) { EXPECT_EQ(9, Solution().romanToInt("IX")); }
+TEST(RomanToInteger, DCXXI) { EXPECT_EQ(621, Solution().romanToInt("DCXXI")); }
+TEST(RomanToInteger, MCMXCIV) {
+  EXPECT_EQ(1994, Solution().romanToInt("MCMXCIV"));
+}

roman-to-integer.cpp

@@ -0,0 +1,109 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <string>
+#include <unordered_map>
+
+using namespace std;
+
+// https://leetcode.com/problems/roman-to-integer/
+
+static inline int table1(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;
+  default:
+    return 0;
+  }
+}
+
+class Solution {
+public:
+  int romanToInt(string s) {
+    int sum = 0;
+    for (int N = s.size(), i = N - 1; i >= 0;) {
+      if (N == 0) {
+        break;
+      }
+
+      char c2 = s[i];
+      if (N == 1) {
+        sum += table1(c2);
+        break;
+      }
+
+      char c1 = s[i - 1];
+      if (false) {
+      } else if (c1 == 'I' && c2 == 'V') {
+        sum += 4;
+        N -= 2;
+        i -= 2;
+        continue;
+      } else if (c1 == 'I' && c2 == 'X') {
+        sum += 9;
+        N -= 2;
+        i -= 2;
+        continue;
+      } else if (c1 == 'X' && c2 == 'L') {
+        sum += 40;
+        N -= 2;
+        i -= 2;
+        continue;
+      } else if (c1 == 'X' && c2 == 'C') {
+        sum += 90;
+        N -= 2;
+        i -= 2;
+        continue;
+      } else if (c1 == 'C' && c2 == 'D') {
+        sum += 400;
+        N -= 2;
+        i -= 2;
+        continue;
+      } else if (c1 == 'C' && c2 == 'M') {
+        sum += 900;
+        N -= 2;
+        i -= 2;
+        continue;
+      }
+
+      sum += table1(c2);
+      --i;
+      --N;
+    }
+
+    return sum;
+  }
+};