Fix #567: Add Radix Sort [C] (#571)

* Added Radix Sort [C]

* Use tabs instead of spaces and add final newline

* Add entry to README.md

* Fix a silly silly bug

Author: sergobot

README.md

@@ -42,7 +42,7 @@ Community (college) maintained list of Algorithms and Data Structures implementa
 | [Prims](https://en.wikipedia.org/wiki/Prim%27s_algorithm) | [:white_check_mark:](prims/prims.c) | | [:white_check_mark:](prims/Prims.java) | | [:white_check_mark:](prims/prims.go) | [:white_check_mark:](prims/prims.js) | |
 | [Quick Select](https://en.wikipedia.org/wiki/Quickselect) | [:white_check_mark:](quick_select/quick_select.c) | | [:white_check_mark:](quick_select/QuickSelect.java) | [:white_check_mark:](quick_select/quick_select.py) | | | |
 | [Quicksort](https://en.wikipedia.org/wiki/Quicksort) | [:white_check_mark:](quick_sort/quicksort.c) | | [:white_check_mark:](quick_sort/QuickSort.java) | [:white_check_mark:](quick_sort/quick_sort.py) | [:white_check_mark:](quick_sort/quick_sort.go) | [:white_check_mark:](quick_sort/quickSort.js) | [:white_check_mark:](quick_sort/QuickSort.cs) |
-| [Radix Sort](http://www.geeksforgeeks.org/radix-sort/) | | | [:white_check_mark:](radix_sort/RadixSort.java) | [:white_check_mark:](radix_sort/radix_sort.py) | | | |
+| [Radix Sort](http://www.geeksforgeeks.org/radix-sort/) | [:white_check_mark:](radix_sort/radix_sort.c) | | [:white_check_mark:](radix_sort/RadixSort.java) | [:white_check_mark:](radix_sort/radix_sort.py) | | | |
 | [Rod Cutting Problem](http://www.geeksforgeeks.org/dynamic-programming-set-13-cutting-a-rod/) | [:white_check_mark:](rod_cutting_problem/rod_cutting.c) | | [:white_check_mark:](rod_cutting_problem/RodCutting.java) | [:white_check_mark:](rod_cutting_problem/rod_cutting.py) | [:white_check_mark:](rod_cutting_problem/rod_cutting.go) | [:white_check_mark:](rod_cutting_problem/rodCuttingProblem.js) | |
 | [Shell Sort](https://en.wikipedia.org/wiki/Shellsort) | | [:white_check_mark:](shell_sort/ShellSort.cpp) | [:white_check_mark:](shell_sort/ShellSort.java) | [:white_check_mark:](/shell_sort/shell_sort.py) | [:white_check_mark:](shell_sort/shell_sort.go) | [:white_check_mark:](shell_sort/shellSort.js) | [:white_check_mark:](shell_sort/ShellSort.cs) |
 | [Sieve of Eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes) | [:white_check_mark:](sieve_of_eratosthenes/sieveOfEratosthenes.c) | | [:white_check_mark:](sieve_of_eratosthenes/SieveOfEratosthenes.java) | [:white_check_mark:](sieve_of_eratosthenes/sieve_of_eratosthenes.py) | [:white_check_mark:](sieve_of_eratosthenes/sieve_of_eratosthenes.go) | [:white_check_mark:](sieve_of_eratosthenes/sieveOfEratosthenes.js) | |

radix_sort/radix_sort.c

@@ -0,0 +1,59 @@
+#include "stdio.h"
+#include <time.h>
+#include <stdlib.h>
+
+/*
+ * Returns maximum number in an array
+ * @a array pointer
+ * @n number of elements in the array
+ */
+int max(int * a, int n) {
+	int max = a[0];
+	for (int i = 1; i < n; i++) {
+		if (a[i] > max) {
+			max = a[i];
+		}
+	}
+	return max;
+}
+
+/*
+ * Performs Radix Sort on a given array
+ * @a array pointer
+ * @n number of elements in the array
+ */
+void radix_sort(int * a, int n) {
+	int m = max(a, n);
+	int b[10] = {0};
+
+	for (int exp = 1; m / exp > 0; exp*=10) {
+		int bucket[10] = {0};
+
+		for (int i = 0; i < n; i++)
+			bucket[(a[i] / exp) % 10]++;
+		for (int i = 1; i < n; i++)
+			bucket[i] += bucket[i - 1];
+		for (int i = n - 1; i >= 0; i--)
+			b[--bucket[(a[i] / exp) % 10]] = a[i];
+
+		for (int i = 0; i < n; i++)
+			a[i] = b[i];
+	}
+}
+
+int main() {
+	srand(time(NULL));
+	int n = 10;
+
+	int test_array[n];
+	for (int i = 0; i < n; i++) {
+		test_array[i] = rand() % 1000;
+	}
+
+	radix_sort(test_array, n);
+	for (int i = 0; i < n; i++) {
+		printf("%d ", test_array[i]);
+	}
+	printf("\n");
+	return 0;
+}