0012 and 0013 done in c

solution/0000-0099/0012.Integer to Roman/README.md

@@ -300,6 +300,30 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+static const char* cs[] = {
+    "M", "CM", "D", "CD", "C", "XC",
+    "L", "XL", "X", "IX", "V", "IV", "I"};
+
+static const int vs[] = {
+    1000, 900, 500, 400, 100, 90,
+    50, 40, 10, 9, 5, 4, 1};
+
+char* intToRoman(int num) {
+    static char ans[20];
+    ans[0] = '\0';
+    for (int i = 0; i < 13; ++i) {
+        while (num >= vs[i]) {
+            num -= vs[i];
+            strcat(ans, cs[i]);
+        }
+    }
+    return ans;
+}
+```
+
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 <!-- solution:end -->

solution/0000-0099/0012.Integer to Roman/README_EN.md

@@ -298,6 +298,30 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+static const char* cs[] = {
+    "M", "CM", "D", "CD", "C", "XC",
+    "L", "XL", "X", "IX", "V", "IV", "I"};
+
+static const int vs[] = {
+    1000, 900, 500, 400, 100, 90,
+    50, 40, 10, 9, 5, 4, 1};
+
+char* intToRoman(int num) {
+    static char ans[20];
+    ans[0] = '\0';
+    for (int i = 0; i < 13; ++i) {
+        while (num >= vs[i]) {
+            num -= vs[i];
+            strcat(ans, cs[i]);
+        }
+    }
+    return ans;
+}
+```
+
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 <!-- solution:end -->

solution/0000-0099/0012.Integer to Roman/Solution.c

@@ -0,0 +1,19 @@
+static const char* cs[] = {
+    "M", "CM", "D", "CD", "C", "XC",
+    "L", "XL", "X", "IX", "V", "IV", "I"};
+
+static const int vs[] = {
+    1000, 900, 500, 400, 100, 90,
+    50, 40, 10, 9, 5, 4, 1};
+
+char* intToRoman(int num) {
+    static char ans[20];
+    ans[0] = '\0';
+    for (int i = 0; i < 13; ++i) {
+        while (num >= vs[i]) {
+            num -= vs[i];
+            strcat(ans, cs[i]);
+        }
+    }
+    return ans;
+}

solution/0000-0099/0013.Roman to Integer/README.md

@@ -341,6 +341,32 @@ def roman_to_int(s)
 end
 ```
 
+#### C
+
+```c
+int nums(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;
+    }
+}
+
+int romanToInt(char* s) {
+    int ans = nums(s[strlen(s) - 1]);
+    for (int i = 0; i < (int) strlen(s) - 1; ++i) {
+        int sign = nums(s[i]) < nums(s[i + 1]) ? -1 : 1;
+        ans += sign * nums(s[i]);
+    }
+    return ans;
+}
+```
+
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 <!-- solution:end -->

solution/0000-0099/0013.Roman to Integer/README_EN.md

@@ -327,6 +327,32 @@ def roman_to_int(s)
 end
 ```
 
+#### C
+
+```c
+int nums(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;
+    }
+}
+
+int romanToInt(char* s) {
+    int ans = nums(s[strlen(s) - 1]);
+    for (int i = 0; i < (int) strlen(s) - 1; ++i) {
+        int sign = nums(s[i]) < nums(s[i + 1]) ? -1 : 1;
+        ans += sign * nums(s[i]);
+    }
+    return ans;
+}
+```
+
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 <!-- solution:end -->

solution/0000-0099/0013.Roman to Integer/Solution.c

@@ -0,0 +1,21 @@
+int nums(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;
+    }
+}
+
+int romanToInt(char* s) {
+    int ans = nums(s[strlen(s) - 1]);
+    for (int i = 0; i < (int) strlen(s) - 1; ++i) {
+        int sign = nums(s[i]) < nums(s[i + 1]) ? -1 : 1;
+        ans += sign * nums(s[i]);
+    }
+    return ans;
+}